Max has grown to his full potential and is now wiser than in any other series. Since Alien Force, he's been trying to be protective around Ben, Gwen, and Kevin. He makes his first reappearance in the episode Hit 'Em Where They Live, it is revealed that Max has been protecting Ben's parents from being attacked by Ben's old enemies (due to Ben's secret being revealed to the universe). However he is injured while protecting Sandra from Sevenseven and is forced to inform Ben and his team of the problem.
Max appeared again in Ultimate Aggregor and Map of Infinity, where he helps Ben, Gwen, and Kevin stop Aggregor. However, in the beginning of Map of Infinity, Ultimate Aggregor's electrical shock damaged his entire nervous system, and must be replaced. Azmuth brings him, along with Ben and his team to Galvan Mark II, where Max is placed in a tube that would repair his nervous system after a few weeks.
Grandpa Max returns in Moonstruck, where he reveals his past where he first met Verdona to Ben, Gwen, and Kevin (who sleeps after hearing the story). When he was about Kevin's age (16 or 17), he was a pilot in the air force. During a mission, he saw and followed a space ship. He blasted it, but the space ship got away and Max's plane crashed. He talked to the commander about the space ship, which made him an astronaut and gave him a mission to be the first man on the moon. While at a saloon, he met Verdona in her human form and fell in love with her. Suddenly, a giant human robot came and attacked Verdona. Max saved her and left to a far away desert where the robot couldn't find them. Verdona explained to Max that she is not from Earth, she is from another planet. The robot that chased them was a sentient robot called a Synthroid and it left a bracelet on Verdona's hand, which made her unable to do most her powers, save for her telepathy. She revealed to Max that she was the one in the spaceship he saw before she read Max's mind. She told him that their minds are now linked. She also revealed that the Synthroid wants her to be a battery-like energy source for their planet (since she is an energy being). The Synthroid came back and kidnapped Verdona, but Max used his mind to locate Verdona (since Verdona said their minds are now linked). He (with a help from Magister Labrid) saved Verdona and destroyed the Synthroid.
Verdona invited Max to her planet, but Max denied the offer, saying that he has other things to do on Earth. They kissed and Verdona left. The next Monday, he went into astronaut training. Eventually, Max joined the Plumbers after Magister Labrid recruited him. He told Ben that was the story of how he and Verdona met later and said good night to Verdona before he went to sleep.
Max appeared once more in Prisoner Number 775 Is Missing when Area 51 was attacked and was furious when he learn of its alien prisoners being held there illegally and as a result had caused friction between Rozum and Max.