Before the events of the franchise, Hämsterviel worked alongside Jumba Jookiba as scientist. Together, they made genetic illegal experiments. However, because of the chaos the experiments caused, Hämsterviel and Jumba were arrested and sent to prison. Oblivious to Hämsterviel, Jumba was released to capture his latest experiment 626. During these events, Jumba reformed and spent his days on earth with a new family. Eventually, Hämsterviel would escape, recruits the former captain of the Galactic Federation as his henchman, and seek to regain "his" experiments. Hämsterviel's attempts failed but the constant failures did not prevent the mad scientist to trying again. Years after these event, Hämsterviel sets out to harvest absolute power instead.
Hamsterveil seems to have a bit of a Napoleon-complex, as despite his short stature, he has a large imposing character and wants nothing less than total galactic domination.
He is cunning, diabolical, and very abusive to his employee, Gantu, whom he frequently assaults with a plethora of poorly-sarcastical insults but nevertheless demeaning. He doesn't care about his minions so long as they serve him competently but despite Gantu's loyalty, as well as helping him escape jail in Leroy and Stitch, he promptly fired Gantu after Hamsterveil's objectives had been achieved, saying that since he had Leroy, he didn't need Gantu.
Hamsterveil also hates his old business partner, Jumba, as well as Stitch, Lilo, Pleakley, and later, Yuna. His schemes have sometimes been directed at them, either to enslave them, or even kill them. Originally, he schemed to take the 625 experiments Jumba created before Stitch, and use them in his bid to conquer the galaxy, viewing the experiments as his own property because he financed their creation using his shady buiness deals.
Role in Reconnect
Hamsterviel makes his debut in the third visit to Kuaui as a member of Maleficent's alliance. Hamsterviel plots to use Jumba's experiments to take over the galaxy along with his new sidekick Capatain Gantu.
In the fourth visit, Hämsterviel escapes prison and forces Jumba to create a new experiment, "Leroy." He then repeatedly clones Leroy and uses the clones to take over the Galactic Alliance, firing Gantu afterward for his incompetence. This proves to be the key to his downfall, as Gantu breaks Lilo and 625 out of prison. When Hämsterviel goes to watch Leroy and his clones destroy the other experiments, his plan is thwarted by the arrival of the reformed Gantu, Lilo, Stitch, Reuben, Jumba, and Pleakley, who team up with all the other experiments and defeat Leroy. After Lilo, Stitch and Reuben defeat all of the Leroy's with Aloha Oe, the remaining angry experiments toss him around like a beach ball causing him to yell "I am not beach ball like, I am hamster like!" Hämsterviel is sent back to prison afterward, with all the Leroys in the cells around him. This eventually leads to Maleficent abandoning to his prison cell for failing her for the last time.