Kevin "Sif" Hunderson is the main protagonist in Sif 100: Alienated!
Sif wears a red short-sleeved jacket with collars. Theres a large "1" in the center of the right side of his jacket, and "00" in the center of the left side. Under his jacket, he wears a black shirt, with red lines similar to Ben Tennyson in OS. He also wears jeans, and red converse shoes. He wears the Alphatrix on his left arm.
Sif has brown hair and dark brown eyes, that turn more red because of the Alphatrix.
Sif has a jokey attitude most of the time, but he is really smart. Sif doesn't really get mad or upset all that often, he tries to joke a lot, and be happy. With his friends, he is especially jokey. Sif can also have an inappropriate attitude at times. As Alienated, he tries to be more serious but always ends up making at least one joke. He feels he can be something more as Alienated, rather than living a normal life. But, Sif sometimes feels as though hes insane and out of control.
Sif has no real abilities, but he is smart. He is good at his job, which is being a detective. But, with the Alphatrix, Sif has the abilities to transform into 100 Aliens or more. (Only confirmed Aliens; Ultimates and Alphatrix included:)
Sif is a Human, with all Human weaknesses. But, the Alphatrix and the Aliens itself do have weaknesses.
- This is the very first Sif 100 series to address Sif as his real name, "Kevin".