The group at a hotel in New York City. While Grandpa Max is at the main desk, checking everyone in, Ben spots an area where they are featuring a new Sumo Slammers video game. He runs towards the area, yet he is blocked by a security guard at the front. So he transforms into Ghostfreak and passes through the entrance, but when the guard catches him, they all get thrown out of the hotel.
While Grandpa Max is out trying to get his money back from the hotel, Ben decides to head off by himself in the city and with Gwen following him they end up in an arcade. Here they meet Kevin, a boy that helps Ben after a game eats his money. Kevin sends an energy surge with his hand into the machine, causing it to dispense all the tokens that were in it. But as Ben collects the money, a group of bullies attacks Kevin, calling him "freak", so Ben transforms into XLR8 to save his new friend.
While Gwen heads back to the RV, and explains that he was born with his powers and that his parents abandoned him because of it (although it isn't clear if Kevin's parents kicked him out of home, or if Kevin decided to go away on his own). Kevin then asks to Ben about his grandfather, who was mentioned by Gwen. Ben explains that he was grounded after sneaking in to play a game that has been unreleased. Hearing Ben mention the Sumo Slammers game, Kevin gets an idea and the two head off to a storage warehouse near the docks, where Kevin uses his power to break in the security door and shows Ben that that is the place where the new game is kept. But then they are discovered by the police, and after a failed attempt at escaping, Ben transforms into Stinkfly and holding the other boy he flies away.
After seeing what the younger is capable of, Kevin proposes they become partners and that together they should be able to do anything they wish. Ben agrees, and shakes their hands to finalize their agreement. Inside the subway system, Kevin absorbs energy from a lamp, then walks over to the train track switcher, and uses the obtained energy to activate it. The track switches, and Kevin explains to Ben that this will cause a collision between a money train and a regular passenger train, and tells Ben to take the cash by using XLR8. Ben immediately is against his plan, and says that hundreds of innocent people will be killed in the process. Kevin however doesn't show any consideration for those people and Ben finally decides to stop him, before it is too late. So Ben tries to transform into Four Arms but transforms into Heatblast instead. But Kevin absorbs Heatblast's energy, and uses it to partially transform into Heatblast himself. Ben manages to save the two trains and escape, and Kevin decides he will get his revenge with the help of the new power.
When Kevin attacks the bullies hideout, Ben arrives and transformed into Four Arms (even though he tried to go Stinkfly) and defeats Kevin, even after he absorbs Four Arms energy and turns into it himself. But when Ben reverts to human and offers Kevin to join him and his family, Kevin attacks Ben again, trying to take the Omnitrix away from him but it releases a pulse that sends Kevin flying.
Back at the RV everyone is glad everything ended, but as Grandpa Max says Ben will have to earn his trust back and Ben rents what he had done, at the subway Kevin is shown using Heatblast's powers while remaining human and laughing maniacally.
The episode starts in an unknown city, where the Tennysons wait in a long line to buy a newly released game, a game that Ben refers to as Sumo Slammers 2.1. Gwen infers that he has the game, but he explains that it’s version 2.1, and that there is a big difference. Gwen can’t wait any longer, and insists that they should go somewhere cool from the heat. So, they decide to enter a nearby bookstore. Later, as they come back out of the store, Gwen wonders how Ben’s doing after waiting for so long. The line is no longer there, but Four Arms comes out, and he causes rampage with the police. Gwen and Grandpa Max are shocked, as they interpret that Ben is the one to blame. The SACT arrive, and prepare to capture Four Arms . Before doing so, Gwen runs up to him, and tries to stop him. With no luck, he continues and ends up being shot by the SACT. Unfortunately, Four Arms leaps off, and leaves them behind.
At the RV, Gwen is infuriated by Ben’s recent actions over a video game. Ben appears to be calm and quiet as he plays his new game. While Gwen interrogates Ben, he says that he has been at the RV the whole time. Gwen tries to take the information out of him by showing him a clip of Four Arms destroying the city as evidence. Grandpa Max seems to be on Ben’s side, though Gwen has a good point. So, Ben tries to prove her wrong by going out to the city to find clues to solve the mystery.
Ben spots Four Arms in an alleyway, and he goes after him. He attempts to activate the Omnitrix to transform into XLR8, though no luck. Ben finds Four Arms at the top of the US Mint building, and Ben decides to go after him. Inside, Gwen and Grandpa Max seem to find Ben anywhere, but they soon find Heatblast attacking the place. Gwen heads to him and insists that he should stop what he’s doing. Heatblast doesn’t seem to be listening to her order. Out of nowhere, Ben appears in front of Grandpa Max behind her. She then realizes that Ben is telling the truth about the alien whose impersonating his alien forms. Heatblast attempts to attack back, but Diamondhead appears just in time to protect her.
Diamondhead prepares to fight Heatblast, but he is stopped by coins that were held in a large container above him. As Heatblast arrives before him, he reveals his true identity. It was Kevin, the teenage sociopath who Ben has met before. This time, Kevin seems to have mastered morphing into a perfect copy that of Ben’s original forms, and Kevin has been using them to ruin Ben’s reputation as a hero.
Kevin transforms into Stinkfly, and flies away, leaving Ben behind with the authorities. Diamondhead tries to explain that he is not the one responsible for such actions. They don’t seem to believe him, and Gwen comes by to back his story up. So Ben has no other choice but to fight. As he runs off, Diamondhead looks for an area to hide. Two soldiers find him, and shoot him, but Diamondhead counters back by knocking the platform down. As Diamondhead continues to try and find a way out, he is again detected, but this time, he is trapped between. To make matters worse, the Omnitrix is about to lose power. As he brainstorms for an idea, he jumps down, and he transforms back to normal just in time. He fakes an act by appearing to protect himself from Diamondhead.
As Ben returns to Gwen and Grandpa Max, Gwen is relieved to see Ben again. The SACT leader, Steel, somehow is suspicious of Ben’s watch, though he lets them through, but orders his troops to follow them, just in case. In the RV, they discuss with each other with what’s happened so far. Gwen finds news headlines on the Internet, and it seems that Kevin has been busy using Ben’s alien forms to wreak havoc in major cities.
All of a sudden, a trolley train is shown heading down the street, and Ben decides to help out. It seems to appear that Kevin is using Upgrade to take control of the car. As Ben tries to transforms into Upgrade, he changes into Wildmutt instead, but there is no other choice but to use what he has now. As Wildmutt runs to the rescue, it seems that the SACT has also been tracking them.
Inside the car, the driver tries to stop the car, but Kevin pulls it out, which makes their situation worse. Wildmutt is behind them, and eventually gets on top of the car. Kevin finds him, and tries to get him off, though Wildmutt was able to get inside the car. Behind the car, Grandpa Max pilots the RV, transformed into its aerodynamic form. Inside the car, Kevin was able to get Wildmutt down, and he tries to get away with it by leaving and flying off with Stinkfly. The car continues to move, and it is headed to a nearby pier. Grandpa Max gets close enough and tells Ben to get on the RV to throw a grappling hook to put on the car. Grandpa Max did all he could do to brake the movements. Before the car fell to its doom, Grandpa Max and Wildmutt were able to save everyone inside it.
Later at night, the RV stops in a parking lot, and Grandpa Max and Gwen come out. It seems that they were there to pick Ben up after the incident. In an unfortunate situation, the SACT was there to take the Tennyson family down, after seeing that they were involved with the alien business. The leader continues to be suspicious of the Omnitrix, but before doing anything else, they receive a report that there is a crystal alien on the loose. The Tennysons get away at this time, though he says he’s not over with them yet.
While Lieutenant Steel gets down to the bridge to deal with Kevin, he’s no match for him, and he beats him up. Four Arms was there in time to save him. As he begins to fight Kevin, the SACT readies their weapon. Gwen says that they should not, because it might hit her cousin also. Steel gives an order to his troops not to shoot until on his command. As Diamondhead is no match for Four Arms’ strength, he turns into Heatblast, which he was able to have a slight advantage. However, Four Arms was able to knock him into the air, but he turns into Stinkfly. Before Stinkfly was able to attack Four Arms, he transforms back into Kevin. Four Arms comes up to him, readying a punch, though Ben did not want to destroy him. He says that he was not worth it, and he never was. With that, Kevin felt extremely angry, and he immediately transformed into a mixture of the different aliens. This time, Kevin had the advantage, but Steel commands his men to shoot Kevin. With this, they successfully take him down, and he falls from the top of the bridge, down to the deep ocean water. Steel realizes that Four Arms is not an enemy, and Four Arms leaves him behind.
As the Tennysons drive off to their next destination, Lieutenant Steel stops them to have a talk with them. He wonders why aliens show up all of a sudden when they are there, but he lets them go. As they drive off, Kevin’s status is unknown, as the dark ocean shows a small area where he fell(and the water starts bubbling).
The episode starts in the middle of an open field with modern windmills. In the street, Ben's Grandpa Max and Cousin Gwen are semi-conscious inside their overturned RV. Ben, as "Diamond Head", is fighting Kevin, who is still in his mutated form of combined, Omnitrix, aliens(from an earlier episode). Before Diamond Head can counterattack, Kevin squirts a greenish fluid(using Stinkfly's ability) to distract him. Kevin carries him up to the air, then drops him, knocking one of the windmills down. Diamond Head responds by throwing the windmill blades at Kevin. Realizing that they match each other's powers, they prepare to attack "normally" by running towards each other. Suddenly, a red beam appears from above, enshrouding them, and they seem to disappear. Gwen and Max get out of the RV, and find Ben missing.
In a dark room, the red beam releases Diamond Head, and a spotlight hits him. As he scans the area, an announcer says the "challenger" comes from planet Earth; it seems that he has been transported to a fighting arena complete with a variety of alien spectators. While Diamond Head is distracted by his unfamiliar surroundings and situation, a droid attacks him from behind. The droid has two scythes for appendages. Viewed from overhead, the arena is separated in sections, each containing fighters against a similar droid. Diamond Head is able to destroy one scythe, but the droid is strong enough to crack through his crystalline body. Diamond Head realizes that it’s time to become serious, so he slices through the robot’s legs, which seems to disable the machine. As the crowd cheers, it seems that someone has been watching his every move.
Meanwhile, Kevin is in the same situation in an adjacent section, and does the same. He uses different powers to defeat the droid. In a flash, he is victorious, and the crowd cheers for him. It seems that the same person has been watching his every move, as well. As Diamond Head gloats, the Omnitrix deactivates, and the audience is surprised by the transformation. The damaged droid is able to get on top of Ben, but Ben is fast enough to use one of the detached scythes to severely puncture and terminate the droid. In an holographic projection overhead, the mysterious being who has been watching them announces his plans to use them for subsequent, staged battles for profit. As the wall between Ben and Kevin opens up, Kevin blames Ben for their current situation, but before Kevin can attack the now-defenseless Ben, they are teleported somewhere else.
Kevin and Ben continue to quarrel, but are stopped by hovering robot guards with stun lances. The robots then attach a device to each of them. Ben and Kevin discover that they are on an intergalactic spaceship, in a room with aliens from various planets, who appear to be in the same situation as themselves. Ben insists they should find a way home, but one alien says that the ship is their home, and there is no way out. Still angry at Ben, Kevin grabs him, but the implanted devices create an electrical discharge between them, forcing Kevin off Ben.
An alarm sounds off, and an alien says that it is meal time. The ceilings open and release a gooey, purple-colored substance. Ben doesn’t have the appetite for the alien glop, but the aliens urge him to eat, because "Technorg" will take their food. The sound of heavy footsteps is heard from the background, and a large, orange, alien appears. It is Technorg. As he approaches the aliens, they kneel down to him, while he takes their food. Kevin, still sitting at the table, sneakily uses his "XLR8" tail to throw one of the trays on Technorg’s face, and blames the act on Ben. Technorg grabs Ben, and throws him aside. To match his power, Ben transforms to "Four Arms", and returns the attack. Out of view, the mysterious alien continues to watch and be intrigued by Ben’s talents. Ben and Kevin are then transported to another area, where the alien identifies himself as "Slix Vigma", who decides to link Kevin and Ben using an electronic shackle, telling them that what happens to one will happen to the other. Slix then transports them to the arena, where they are to fight Technorg.
As Technorg attacks, Four Arms and Kevin run in opposite directions, forgetting that they are now linked. The mistake allows Technorg to grab a hold of the link and throw both of them down. At that moment, the Omnitrix powers down and Ben is returned to his normal form. Kevin tries to get rid of the once again, helpless Ben, forgetting that if Ben is injured or dies, the same will happen to Kevin. Technorg tries an aerial punch, but Kevin is able to dodge the attack. Kevin then runs away from Technorg, dragging Ben on the arena's dirt floor. Kevin continues to humiliate Ben, but Ben attacks Kevin back by tripping Technorg on top of Kevin. Ben insists that if he and Kevin work together, they can defeat Technorg, but Kevin refuses to accept. Instead, Kevin tries to prove that he can win the battle by himself, by alternately shooting "Stinkfly's" goo and "Diamond Head's" diamond shards at Technorg, which does virtually nothing to the seemingly indestructible Technorg. As Ben finishes his pleas for Kevin's cooperation, Kevin uses "Heat Blast’s" fire balls, which explosively ignites Stinkfly’s goo. He tells Kevin to try that combination of powers. It works, with Technorg forced off his feet from the explosions. Ben tells Kevin to use a different combination, and with two powerful punches, Technorg is knocked out. Slix orders Kevin to finish him off, but before he can do so, Ben stops him. Kevin continues to fight with Ben, but are stopped by guards. They are given the title of "Champion", and are taken back to the holding cell.
The imprisoned aliens now pay homage to Kevin and Ben. Technorg appears with a tray of food for Ben, who he is honored to serve, not only because he bested him in battle, but for sparing his life, as well. Ben doesn’t want to be Technorg’s master, and asks if he knows a way off the ship. Technorg says that they have all tried, but it is impossible. As the ship is being prepared to travel to another galaxy, Ben declares that together, they can escape.
A few moments later, as Ben slumps in a corner of the cell, he signals the others to start the plan, and they relay the signal to Kevin who pretends to act out of control. As the robot guards watch, the aliens pile on Kevin, and a flash appears. Ben, now as "Gray Matter" has managed to sneak inside a robot guard, and disable their control devices. Everyone escapes out of the holding cell. Still linked together, Kevin and Gray Matter try to look for the controls for the emergency escape pods, but Slix is able to track them down, and his drones are well-armed with giant axes. Slix was able to capture the other escapees, and use them as hostages, if they tried to escape again. Kevin and Gray Matter fight the drones to escape and save the aliens from the clutches of Slix, but Ben transforms back into his human form, once again. As the aliens outside are tortured, more robot drones come after Kevin and Ben, who must get to the arena to rescue Technorg from being dropped into a pit of vicious beasts.
Distracted while watching the aliens being tortured, Slix is overcome by Kevin and Ben. Ben insists that Kevin should not destroy Slix, who appears to be an intelligent droid. Kevin, ignoring Ben, is about to destroy Slix, when Ben transforms to "Upgrade" and merges with Slix. Upgrade explains that the droid is actually the main command center for the entire ship. He then finds the control console, and breaks their electric shackle link. As Technorg falls from the platform, Upgrade sends a flying platform to catch him. Slix seems able to regain some of his control, but before he can peel Upgrade off, Technorg knocks him out. Upgrade then teleports the imprisoned aliens and themselves to the escape pods.
As Upgrade activates the escape pod doors, every alien escapes successfully, but Technorg insists on staying with Ben. Upgrade pushes him into the pod. Just as he is ready to leave, the Omnitrix deactivates, revealing Slix Vigma as a robot, grabbing Ben to destroy him. Kevin destroys Slix, saying that he wanted the fun of hurting Ben, himself. He hurls Ben against a wall, and, using Stinkfly's goo, attaches him there. Ben tries desperately to activate the Omnitrix, and, just in time, he changes into Cannon Bolt. Kevin is surprised by the new-to-him alien form. Cannon Bolt bounces off the walls battering Kevin to the floor. He then enters a pod to escape, but Kevin holds the door open, but is stopped by Technorg who has returned to the ship to defend Ben. Ben says they are now even, and as he jettisons off the ship in his escape pod, Kevin feigns a meek smile as Technorg approaches, presumably to bash him for his treachery. The ship, having been previously programmed by Slix, disappears into hyperspace, sending Kevin and Technorg far away.
The escape pod lands on Earth, and Ben tumbles out as himself, apparently overcome by the shock of the rocket travel. Gwen and Grandpa have left the damaged RV and seem no worse for wear. They are glad to see that Ben is okay, as he is them. Gwen asks where Kevin is, and the episode ends with Ben saying that Kevin has found a new "playmate", and that they probably won’t be seeing him for a while.
Back with a Vengeance
A space ship flies by an asteroid belt, and a large block of ice is being taken into the vessel. Inside, aliens speculate the massive rock, and Kevin jumps down and recaps his previous battles. He’s been told of Vilgax, over and over again. He places his hand onto the giant ice, and it melts to reveal Vilgax’s frozen state. The aliens step back after seeing Vilgax, knowing that he is the most feared in the galaxy. Kevin says that they were both after for the same thing. The boy who wields the Omnitrix, and the one who has defeated them both in battle.
The Tennysons speculate the amazing sights of the Niagara Falls, hoping they would find another great summer day. Unfortunately, Gwen finds Ben tweaking around again with the Omnitrix. Ben claims that there might be some way to gain better control of it. As he continues to play around with it, the Omnitrix reacts and starts rotating through different alien silhouettes, making Ben think that he must have gone and busted the Omnitrix again. Ben says Upgrade, and he transforms into Upgrade. With amazement, he tries other commands, and he figures out that the Omnitrix also reacts to thoughts. He has found the master control of the Omnitrix, and he has gained the advantage to use it.
Ben, as Wildmutt, looks down into the river, and he looks back at one of the tourists, asking if they could take a picture of him and his wife (the tourists). He falls overboard, and Ben changes into Ripjaws to come to the rescue. After picking him up from the water, he immediately transitions into Stinkfly to fly them back into the ship, safe and sound. Gwen and Grandpa Max are amazed by the sight they just saw. Back at the ship where Kevin is, he looks at Vilgax, saying that he looks like any other alien he’s fought. Vilgax immediately reacts and fights back, giving him a specific message telling him that he should have never said that. Vilgax throws a pillar straight at Kevin, and pushes him out the window, bringing both of them down into the old Megacruiser battle arena. Kevin says that Vilgax should be grateful for saving his life, but Vilgax gives no allegiance to no one. After closer inspection Vilgax realizes that Kevin is a "Mishappen chaotic amalgam of aliens from the Omnitrix" discovering the connection between Kevin and Ben they decide to team up against him.
Gwen and Max relax to a nice afternoon snack, Stinkfly is up in the trees, and with Ben’s personality, expect him to create more of his crazy jokes unto Gwen. He spits slime into her pudding, and laughs. Ben is happy that he is able to stay alien for as long as he likes. He throws the profit money he’s gained for giving the tourists a ride. Gwen and Max both are very aware of the new feature of what the Omnitrix can do, but they both claim that it might have its consequences. Grandpa Max tells Ben to come to him for a small chat. Stinkfly transforms to XLR8, and instead of listening to what he has to say, Ben runs off with his pudding.
Vilgax analyzes Kevin’s DNA makeup, and he explains that his pattern is the same as Ben’s using this in tandem with Vilgax's already vast knowledge of the Omnitrix he can devise a machine capable of removing the Omnitrix from Ben. Kevin’s impatience lets him talk back. They both admit that they lost to a little boy, but Vilgax says that with his knowledge, and Kevin’s connection with Ben, will give them the victory they need. Kevin immediately wants to get the situation over with, but they can only find Ben if the Omnitrix is active. They find the signal shortly after.
The Tennysons continue to enjoy their day, and Grandpa Max decides to take some pictures. Wildvine comes out of nowhere, and decides to dive into the water and bungee himself back up. In a series of photo shoots, Ben continues to play around with the alien forms, and in the lift, he decides to be embarrass himself in front of a few tourists. In a few moments, Vilgax and Kevin arrive, only to go after one thing. The Omnitrix.
Ben, Gwen, and Max were surprised that Vilgax and Kevin were still alive and well, especially after the major incidents that occurred upon them. Ben attempts to escape as Grey Matter, but Vilgax was able to grab him. Little did Vilgax know that Ben knew how to use the Omnitrix more to his advantage. He transforms to Diamondhead to escape Vilgax’s clutches. With double the problem, and double the enemies, Ben knows that he’s up for a challenge. Vilgax and Kevin both fall down the waterfall while Ben flies Gwen and Max into safety.
Vilgax and Kevin survived the long fall, and Vilgax attempts to track Ben’s whereabouts. He comes down as Cannonbolt. At the RV, Max opens up yet another hidden stash in the RV, and it reveals the device they’ve seen before: The Null Void Projector. Max says that it’s the only way to stop Vilgax and Kevin from coming back to bother them.
Kevin tries his way of luring Ben out of hiding, but Vilgax insists that they do it his way. He says that they should be able to get Ben out by using Grandpa Max and Gwen as bait. Their plan as using them worked, though Max was able to defend by using the Null Void Projector to open up the portal to the null-void. Unfortunately, Diamond Head was dragged in as well, and there is no way to get back, unless the one who holds the projector gun.
Kevin is unfamiliar of the place. Vilgax explains that the null-void is an alternate dimension of the galaxy, where the evil are banished forever a long brawl ensues between Vilgax, Kevin and the residents of the void against Ben. Outside, Max attempts to enter the realm himself to get Ben, but Gwen insists that he doesn’t as he's the only one who knows how to operate the projector. Instead, she decides to head in herself.
Inside the Null Void, Heatblast is being carried by one of the aliens controlled by Vilgax. Ben uses strategy to survive the attacks ordered by Vilgax. Outside, Gwen prepares herself. She wears the Plumber suit as armor and arms herself with a large array of plumber weapons. Inside, she encounters danger, but luckily, Gwen has things to prepare herself.
Kevin and Vilgax continue their search for Ben, while Max continues to hold up the portal. He says that Gwen needs to hurry as the projector only has limited power and is beginning to malfunction. In an instant, Ben and Gwen find each other, and realize that they need to get out of there. Kevin was able to grab a hold of Gwen before they reached the portal that leads them out of the area, and to make it worse, they're surrounded. Ben had no other choice but to give up and save his cousin’s life by giving up the Omnitrix to Vilgax and Kevin, but resets the watch to make things difficult for Vilgax to use. Ben thinks that it would be a simple trade, but Kevin in an instant tossed away his cousin and used a giant device that was used to painfully tear off the Omnitrix from his wrist. The device was held in a spherical container, and Kevin grabs it for himself, saying that he should be able to use it instead of Vilgax. With a large fight amongst themselves in who would get the Omnitrix, Ben and Gwen were just about able to get out of the null-void. Vilgax and Kevin manage to catch up to them and block their way out before they could get there. They use the 'Omnitrix' to distract Vilgax, and Ben decides to face off against Kevin so Gwen can escape. Ben is able to trick Kevin and get out of the Null Void before the portal finally closes, leaving the two villains still trapped inside.
When Ben and Gwen emerge from the portal, they are embraced by Max. Gwen says that she has a present for Ben. At first he thought it was something that they would argue about, but it was something more valuable than that. It was the ball that held the Omnitrix. Gwen said that Ben may be dumb enough to throw it away, but she's not. In the Null Void, Vilgax and Kevin were going after a decoy, which eventually exploded followed by getting attacked by a large worm alien.
In an instant, Ben feels the aliens flow back into his body, and he becomes once more as the boy who was given the power to change into the alien heroes. Grandpa Max tells Ben that he owes Gwen a big-time thanks, but Ben had something else in mind. He transforms into Grey Matter and realizes that he zeroed out the master control. The episode ends with Gwen and Grandpa Max laughing.
A dream version of Kevin appears in Perfect Day, as a hall monitor of a dream version in Ben's school. In the dream, Kevin was human but then changed into his mutated form (which appeared uglier than it used to be probably an exaggeration of Ben's fear of Kevin) and fought Ben. When Ben takes control of the dream, he is able to defeat the dream version of Kevin in one fell swoop.
The Bright Side
Kevin attempted to organize a deal between the Forever Knights and the DNAliens in order to sell them level 5 weapons. However, the deal was interrupted by Magister Labrid, Ben and Gwen. Trying to get revenge, Kevin fought Ben, but was easily defeated while the other villains escaped without paying him. Labrid then forced Kevin to help them finding back the weapon, offering him to avoid problems with the Plumbers then. Though Kevin mainly accepted in order to get his pay, Magister Labrid later sacrificed himself in order to save him from a defective weapon's explosion. This, plus Kevin's interest for Gwen and his desire to become a plumber like his father was, led him to agree in teaming up with Ben and Gwen against the Highbreed invasion.
Argit, an alien conman, meets Kevin in an alleyway to discuss a piece of alien tech Kevin had been looking for only to find out that Argit didn't have it. As Kevin begins to drive away Argit tells him that he knows who has it but it may cost him. Later that evening Kevin offers to repair Max's RV, accompanied by Ben and Gwen. When Kevin is finished Gwen tries to go into the motorhome only to have Kevin stop her.
Gwen and Ben wait patiently and confused as they watch Kevin enter the RV only to be shocked when Kevin speeds away from them. Ben attempts to stop him by turning into a new alien, Big Chill, only to have Kevin evade him in the now tricked out RV. As Kevin gets away Gwen is able to catch up with Ben and is slightly impressed when Ben tells her what happened. Using her powers Gwen is able to find Kevin. Meanwhile, Kevin pulls over to the side of the road to meet up with Argit and shows him the RV he wants to trade for the alien technology he wants. After looking it over Argit says it's worthless but takes it back as soon as he sees the large amount of alien tech installed into it. Argit betrays Kevin by shooting his quils at him, temporarily paralyzing Kevin, and steals the RV for himself. As Argit drives away Kevin is able to move just enough to absorb the concrete ground and regain his strength. He throws a boulder at the far off RV which Argit quickly avoids.
As soon as Gwen and Ben locate Kevin Ben confronts him and begins to tell him off only to find out that Kevin had hid a tracking device in RV and was able to track it using his plumbers badge. Following the tracking signal Kevin, Gwen and Ben are led to a warehouse where they find the RV completely stripped, much to Ben's anger. Suddenly the team hears someone coming and hide only to see Argit walk through the door and into the RV to retrieve a piece of alien tech he had left behind.
As he began to leave Argit was confronted by Ben, Gwen, and Kevin all ready for a fight. Argit busts through the window and runs away with the team right on his tail. Ben quickly slaps the Omnitrix down turning himself into Echo Echo and using his powers he corners Argit in an alleyway. Thinking quickly Argit shoots his quills at the many Echo Echos hitting all but one and also hitting Gwen and Kevin. As Argit prepares to shoot the last Echo Echo, he quickly multiplied himself and used his powers to shoot Argit's quills back at him.
When Argit wakes up he finds himself tied up and with his quills glued to his head. When confronted, Argit tells Ben and Gwen that they can't trust Kevin which Ben begins to agree which offends Kevin making him storm off saying he was done with both him and Gwen. After hitching a ride on the back of a truck Kevin arrived at Vulkanus' lair, who supposedly had the alien tech Kevin wanted.
Because of an earlier experience, where Kevin left Vulkanus to the mercy of the plumbers being charged with possession of some counterfeit isotopes, Vulkanus refused to make a deal with Kevin, until Kevin said he would do anything. Still bitter, Vulkanus forces Kevin absorb a rare alien crystal called Taedenite, planning to use him as a living gem mine.
When all seems hopeless Ben, as Big Chill, and Gwen arrive to save Kevin. Ben ends up destroying Vulkanus's suit, revealing he's actually a tiny alien in a robotic suit, and Gwen was able to free Kevin and make him stop absorbing and removing the Taedinite he's already absorbed. As the heroes left the battle scene Kevin remembered the reason he came and retrieved the piece of alien tech he had been looking for, which happened to be another holoviewer that contained a message from Grandpa Max to Ben, saying that he needed to put together a team of other Plumber's kids.
Saving the Universe
Once the team is taken by Paradox to the entry of the Forge of the Creation, the Rust bucket 3 gets stuck in the Chrono Randomization Barrier. The group is then attacked by Aggregor's soldiers, but Ben, as Terraspin, manages to defeat them. Once out of the ship they try to free the ship, but Ben leans on the Chrono Randomization Barrier and brings a 10-year-old Ben to the present, who attacks the team.
Solved the problem, 2 Ben's, Gwen and Kevin land sharply in the Hands of a Gigantic Celestialsapien female. In the exterior they are attacked By Aggregor, who manages to easily defeat Gwen and Kevin, but the two Bens manage to hold their own against Aggregor for a while longer. However they too are eventually overpowered by him. With the inevitable fate that Aggregor was close to obtaining the power of the Celestialsapien Baby, 10-year-old Ben awakens and tells Kevin to absorb the power of the Omnitrix again. Instead Kevin goes towards 16-year-old Ben and absorbs the power of the Ultimatrix, and mutates for the third time and transforms into Ultimate Kevin. Ultimate Kevin prevents Aggregor easily overwhelms Aggregor, and absorbs his powers as well.
However all of the excess absorbed energy causes Kevin to become mentally unstable once again, and he contemplates absorbing the baby Celestialsapien himself. The words of 10-year-old Ben manage to sway his mind and he departs from the Forge of the Creation, promising to return.
Because his mind was unstable, Kevin is looking for revenge on those who have harmed either him or someone he cared about.
Kevin returns voluntarily to Incarcecon, the Prison in the Null Void. Kevin acts like the other prisoners, but he's planning to kill Morgg, the supreme local commander, who years before, when Kevin was a child, killed another prisoner named Kwarrel, who helped him get control of his powers and escape.
Ben and Gwen look for Kevin at his house. They find an inscription that takes them to the prison, when Morgg is alerted of their unscheduled arrival. They eventually manage to escape and discover his plan of using the prisoners to mine a hallucinogenic powder. Kevin finds Quince, who tries to talk him out of killing Morgg, but Kevin doesn't listen. Once Kevin sees Morgg in the underground tunnels, he attacks him, but Morgg activates the prisoner's necklaces. Ben and Gwen realize how the necklaces work and Ben destroys them, leaving Morgg defenseless. Ben and Gwen find Kevin, who's about to attack Morgg. They try to talk him out of it, but he doesn't listen so Ben turns into Armodrillo to fight him.
The battle causes the tunnel to collapse, which allows Kevin and Morgg to escape unseen. Morgg is headed to an elevator to escape the prison, but Kevin was already waiting for him. Morgg begs for his life, but Kevin doesn't listen and throws him into the elevator and cuts the wire. Luckily, Ben and Gwen are able to save him.
Kevin later chases Argit, and tries to kill him, but Argit escapes and goes to Ben and Gwen for help. Argit is sent to the Plumbers' Academy, where he is almost arrested for his crimes, but he convinces the plumbers not to arrest him and he eventually survives another attack from Kevin, with Ben and Gwen's help.
Kevin attacks the academy in search of Argit and presses the Magister to reveal his location, but Ben faces it since Ultimate Humungousaur. Ben loses the contest and returns to his human form, but before being killed by Kevin, Gwen appears to stop it. Argit tries to liberate the Vreedles Brothers, but these refuse and for Argit's petition they drop a bomb nuclear to Kevin, which threatens to destroy the place. Ben manages to transform in Echo Echo worse it is not sufficient and happens to Ultimate Echo Echo going out with the bomb towards the exterior space and the bomb exploits seemingly killing Ben.
Kevin takes advantage of the moment and attacks Argit making it seemingly dead, escaping of the place. Ben at the time enters again the academy with the Magister, Ben at the time shouts Argit's cuarpo and this one wakes up revealing that became the dead man, Argit is at the time arrested by Vreedle Brothers by order of Magister Coronach.
Hunger for Energy
Due to the fact that all his debts received, Kevin remains free for absorbing energy. Kevin at the time initiates a search for power and vital energy of everyone that he knows. Kevin at the time had easily defeated Pierce, Manny, Helen and the Dr. Viktor, stealing from them their power's and vital life force, killing them or making them seriously wounded. In search of new victims Kevin it attacks Alan in the cornfields, Alan tries to stop Kevin, but this one was a losing battle and manages to steal his power from him. Ben went to the rescue and turned into NRG to save Alan of being absorbed totally by Kevin. Kevin at the time tried to absorb Ben, but he manages to escape and saved Alan of Kevin's assault, to what it escapes.
because of the imminent Threat Ben goes to Gwen, in order to carry out a search To put down Kevin before it ends up by killing more people. Gwen refuses and tries to stop Ben does from killing Kevin, causing a fight and a battle between Ben and Gwen Battles Ben manages To defeat her with Way Big and part ways in search Kevin. Ben pressures The Forever Knights and Vulkanus to reveal information about Kevin without having much Success. Gwen goes to Galvan Prime where Grandfather Max in hopes Ben would stop Ben in his search, but Max says to her that Ben is doing the right thing. Then Gwen looks for Darkstar's Help, who kept the remains of the Dominus Librium, which has the power to cure Kevin of his mutation.
Gwen returns Michael to his original form to him and offers him sufficient mana for one year, for what Darkstar her agrees to help. Then Gwen and Darkstar meet Ben inside a Mine while he was attacking Vulkanus for information, Gwen stop him and says to him that Darkstar agrees to help Kevin return to his old self, but Ben not buying it is stopped again by Gwen. Moment later, the trio goes to Total zone and Gwen enters thinking Kevin is in there trying to stay away from her. The Kevin's hunger for energy takes over. Gwen is caught by Kevin but it calls Charmcaster's Stone Monsters which had liberate her and fight against Kevin. is at the time when Kevin starts absorbing Mana from the Monsters and absorbs Gwen.
Gwen manages to distract Kevin with machines with her spell managing to escape before Kevin steals more of her energy. Ben proving to be opposed to Michael's plan, Michael had brought them to Los Soledad for Cooper's assistance in this matter to get the Dominus Librium working again however Ben believes that they will fail. Kevin searches for Gwen at her house where he battles with Max who is now fully healed. During the battle Kevin has a confrontation with Harvey Hackett, his stepfather. Ben arrives and eventually leads Kevin to Los Soledad. Cooper fires off Los Soledad's missiles at him but Kevin overcomes them. Eventually Kevin is defeated by Ultimate Echo Echo and he is about to be killed by Ben when Gwen manages to convince Ben to go with the plan. Eventually the plan works and Kevin is restored to normal.
In The Rooters of All Evil the Rooters (Servantis, Swift, Leander and Phil), which are a splinter faction of the Plumbers, demand to see Kevin. It is revealed that Osmosians are a subspecies of humans and they are humans born with a special genetic component that gives them unique powers. In reality, neither Osmos V existed nor did Devin Levin. While spending his time in the Null Void Kevin was saved by the Rooters and he was taken to their headquarters. There his powers were used to turn some human children into alien hybrids. These Amalgam Kids were used to do nasty things which prepared them for the upcoming storm. Eventually their memories were wiped and they were set loose. At the end of the episode Kevin escapes and the Rooters vow to return. Kevin is last seen at Undertown giving Argit back his memories.
Kevin and Argit start recruiting all the Amalgam kids and all of them are given their memories back. Eventually they, Ben, Rook and Gwen infiltrate the Rooter's headquarters in Null Void. Servantis takes control of the Amalgam kids and he convinces Kevin to join his side to defeat Ben, the upcoming storm. Ben, Gwen, Rook and Argit escape but they are recaptured by Kevin and his team. Kevin absorbs Ben's Omnitrix and gains a new mutation. In a following flashback it is revealed that Kevin had another mutation, that time it comprised of the other aliens Ben unlocked in the original series. Eventually when Ben is about to be destroyed Kevin intervenes and starts attacking the Rooters. He frees the Amalgam Kids from Servantis' mind control and turns back to his human form showing complete control over his mutation. It is revealed that Kevin was pretending to side with the Rooters so that he could help Ben and the Amalgam Kids.The Rooter's Plumber status is revoked and they are trapped in the Null Void.
In Ken 10 Kevin's son Devlin frees Kevin from the Null Void where he was trapped after he went berserk again. He shows little concern over Devlin and abandons him. Ben and his son Ken start fighting Kevin but they are defeated and Ken is wounded. Enraged Ben transforms into Way Big and starts beating up Kevin but to no avail. Suddenly someone throws a weapon at him and he is transported back to the Null Void. Devlin is revealed to have done this. Eventually he is adopted by Ben's family while Ken earns Ben's trust.
In The End of an Era it is revealed that Kevin has been cured and he is sane again. He is once again part of the team.