Kevin 11

Kevin 11 is a mutated alien monster and Ben Tennyson's nemesis. Unlike the present day Kevin, he is evil and also a unique member of the Organization.

Canon Bio
In the original Ben 10 series, Kevin was a thin and scrawny boy with shoulder-length raven hair, pale skin and dark brown eyes with black-discolored marks around them (a sign that an Osmosian has recently absorbed energy). He wore a torn black t-shirt, black studded arm bands, brown cargo shorts, gray knee-length boots, and a padlock necklace which was a spoil from his first crime: stealing a bike and using it to run away to New York. After absorbing an Omnitrix feedback, Kevin becomes able to transform into exact copies of all of the unlocked aliens, missing an Omnitrix symbol. After the energy overwhelms Kevin, he mutated into Kevin 11, a random mixture of body parts from the 10 said aliens which completely destroyed his clothes, except for his cargo shorts.

Appearance in Ultima
Since the present day Kevin is reformed and long before the AntiHero project, the Organization began playing around with the timeline in an attempt to drag villains from the past and future into their Organization.

While in the Org, Kevin has become powerful, but is also strong-willed and defensive. In some stories, he has developed feelings for Azula and starts casually hitting on her with no success. Eventually, the two instead became friends and have been pretty close. An Organization Christmas and An Organization Halloween gives light to their relationship and shows how close as friends they really are. There will be a non-canon chapter in Pairings which will pair up Kevin and Azula as a couple.