Cooper's History
Ben 10
Cooper first appeared in Ben 10 vs. the Negative 10, where his grandfather asked Max to pick Cooper up from summer camp. He later proved critical to stopping the Negative 10, from saving Ben at Fort Knox, to upgrading the Rust Bucket, and reactivating the Mt. Rushmore base defenses. However, he was put under Sublimino's control, and turned on his friends. Gwen managed to knock him out, and he remained unconscious for the rest of the episode. He wore a white shirt with purple suspenders.
At some point after these events, Cooper developed a crush on Gwen.
Five Years Prior to Omniverse
In the flashback episode From Hedorium to Eternity, Cooper is called in by Ben to create a camera to spy inside Thaddeus J. Collins' house. Cooper is initially reluctant, but changes his mind after he hears Gwen's name. The surveillance spider Cooper creates infiltrates the house, but gets stuck underground, with no signal.
Cooper joins Ben and the others in further investigating the matter. As they go inside the house, he offers to hold Gwen's hand, but she declines. Travelling into the caves beneath the house, they encounter Kevin, who has been enslaved by Collins to mine Hedorium. As Cooper works on making Kevin more mobile, Kevin taunts him over his crush on Gwen, telling Cooper that he's the better guy.
Not long after, they discover that Collins has been possessed by Zs'Skayr, who plans on bringing an invasion force of Ectonurites to Earth. In the battle that follows, Cooper succeeds in reversing Zs'Skayr's portal, sending him and his servants back to Anur Transyl.
Alien Force
In Undercover, Cooper returned, having met Kevin on a prior occasion. Kevin suggested recruiting him to repair a teleportation device. When they arrived at his lab, they found it ransacked and Cooper missing. Cooper left a message showing him being captured by DNAliens. When they arrived at Los Soledad they discovered that Cooper's technopathic abilities were used to make a powerful energy source, a large cloaking device, and were being used to build the arch. With Cooper's help the cloaking device is destroyed and a trucker spots the chaos who alerts the police.
In War of The Worlds, Cooper is recruited in a last stand attack on Los Soledad. He uses his abilities to free Darkstar, and create a weaponized robotic suit to fight the DNAliens and later lasers that turn DNAliens back to normal. After the chaos is over Cooper joins Manny, Pierce, Alan and Helen as pupils under Grandpa Max.
In Vengeance of Vilgax: Part 1, Cooper tried to stop Vilgax with his suit and failed.
Ultimate Alien
Cooper returns in Absolute Power: Part 2, where he had experienced a growth spurt and is now tall and built, possessing a similar body shape as Kevin, being different from when he was short and chubby. He retains his big crush on Gwen, but Gwen is focused on saving Kevin. He agrees to Darkstar's plan to create a device to power the Dominus Librium to revert Ultimate Kevin. When he approaches Los Soledad, Darkstar reminds Cooper that the area is an abandoned military base, and realizes that the area would obviously be filled with weapons, though they are no match for Ultimate Kevin.
Cooper later charges Ultimate Kevin in retaliation for attacking Gwen, though Ultimate Kevin outmatches him and tries to kill him though he is saved by Ultimate Echo Echo. Ultimate Echo Echo whispers something to Cooper. After Ben prevented Michael Morningstar's reappearance, he explains that he knew Darkstar's plan all along and told Cooper to build a mechanism to prevent Darkstar from gaining the power if he were to absorb the Dominus Librium, which he did. Afterwards, Gwen kisses Cooper on the cheek. He then witnesses, much to his chagrin, Gwen and Kevin sharing a passionate kiss on the lips.
In Prisoner Number 775 Is Missing, Cooper is seen in a Plumber suit, telling Max Tennyson that Area 51 is gone and nothing was left but a giant hole. He also told him that whatever the Air Force had learned, they would never tell him. He added that no one knows technology like him and he had never seen anything like that. Later, when Max, Ben, Gwen, and Kevin arrived, he sees Gwen and stares at her while smiling.
