|The Enemy of My Enemy|
|Original broadcast||December 3, 2010|
|Series||Ben 10: Ultimate Alien|
|Overall episode number||116|
|Written by||Len Uhley|
|Directed by||Matt Youngberg|
The Enemy of My Enemy is the eighteenth episode of Ben 10: Ultimate Alien.
In a small hut, the Vreedle Brothers' father speaks with Argit, saying he enlisted them to the Plumbers' Academy, but are failing in their exams. He is sending Argit to change their scores or he shall get a bad punishment for not doing so.
While taking a ride in Ben's car, Ben and Gwen discuss that Kevin is still continuing his endless rampage on everyone that wronged him and that he needs to be taken care of. Just then, Ben accidentally runs over Argit, but he still manages to survive. Argit explains that he needs their help in order to hide from Ultimate Kevin, who he met earlier when he came to earth for some supplies from Ultimate Kevin, but finds Kevin in his monster form and attacks him for all of his double-crossing, but Argit was able to escape. Argit says that they need to hide him from Ultimate Kevin, so they suggest a few places until they settle on the Plumbers' Academy, which Argit only agrees to go to because he needs to fulfill his promise to Mr. Vreedle. While on the way there, Ultimate Kevin attacks them. Ultimate Kevin uses Big Chill's intangibility and goes inside the jet asking for Argit. Ben becomes Jetray and tries to fight Ultimate Kevin, but Ultimate Kevin is too strong. Gwen activates the air-lock, which sends Ultimate Kevin out of the jet, but he only leaves them so he can save his falling car.
The group arrives at the Plumber's Academy, where they are greeted by the headmaster Magister Korwak, but he is not happy to see Argit with him. The headmaster has ordered to take Argit to a cell while he talks to Ben and Gwen about bringing Argit here so he can escape from Kevin. Meanwhile, Argit fakes having to go to the bathroom, with his escort taking him and before he could realize it was a trick, Argit uses his quills to stun him. Argit then begins looking around for the students' grade room, but unfortunately ends up in a cafeteria filled with students. The Vreedles are also there and Argit tells them about their plan, but to keep a low profile by not acting who Argit is. Argit does find the room and changes the scores, but the Plumbers' Academy is shocked when Ultimate Kevin arrived.
Ben and Gwen confront Kevin when he goes inside and attacks the students defending the school. Ben becomes Humungousaur to fight Ultimate Kevin, but Ultimate Kevin is stronger. Ben changes into Ultimate Humungousaur for more power to fight Ultimate Kevin, but Ultimate Kevin still reaches the upper-hand and defeats Ben. As Ultimate Kevin was about to kill Ben, Gwen tries to stop him while Ultimate Kevin begins arguing with her. Then, Ultimate Kevin sees Argit, which makes him remember why he is here and tries to get Argit. Argit quickly runs back to the Vreedles and tells them he needs their help to fight Ultimate Kevin and the Vreedles unzip a bunch of weapons. Argit and the Vreedles come back and Ultimate Kevin begins throwing Argit around the room hard. The Vreedles launch a bomb at Ultimate Kevin, but had no idea that the bomb will destroy the school and everyone inside it. Ben wakes up in the nick of time and transforms into Echo Echo to stabilize the bomb using sonic cries, but it doesn't work, so Ben transforms into Ultimate Echo Echo and takes the bomb using his sonic disks into space and holds it together until it explodes. As Ultimate Kevin was about to finish Argit off, Gwen stops him, causing Ultimate Kevin to get really mad, but a little bit of his sanity helps him spare Gwen's life. Ultimate Kevin leaves, thinking Argit to be dead, but Argit was able to shut off his pulse so Ultimate Kevin would think he would be dead. The headmaster orders the Vreedles to arrest Argit for bringing assault of two cadets and 14 acts of warrants for his arrest and Ben and Gwen wonder if Kevin could really become sane and normal again.
- When Ben is talking to Gwen in his car, he loses the stripes in his right sleeve.
- In one of the scenes where Ben is talking to Gwen, his tongue is the same color as his skin.
- In the scene where Ben, Gwen and Argit are discussing where they're going to hide Argit, Gwen's collar was red instead of white.
- The episode keeps switching between Argit's jacket having a line on either side and having one line on the left side
- When Humungousaur evolved, the 4 spikes are not popping out of the right sides of his Ultimatrix symbol.
- In the scene where Ultimate Echo Echo was flying, one time he has light blue colored feet, like his shoulders, and another time he has blue feet like his regular skin.
- Ultimate Echo Echo should not have been able to use his powers in space as sound requires a material medium and cannot travel in a vacuum.
- This episode is from the expression "The Enemy of My Enemy is My Friend."
- FusionFall released an Ultimate Humungousaur set in relation to this episode.
- It is revealed that Ultimate Echo Echo can survive in the vacuum of space.
- It is revealed that Argit's species can shut off their pulse.