Devlin Levin is Kevin 11,000's son, Kenny's best friend, and later, Ben 10,000's adoptive son. When they first met, Devlin tricked Kenny into leading him to a Null Void Projector which he used to free his father.
Devlin bears a striking resemblance to Kevin 11,000 when he was his age. He is tall for his age, has long black hair pulled back in a straight ponytail and the sides of his head are shaved, he also has dark blue eyes and pale skin. He wears a dark gray short sleeved hoodie, a black long sleeved shirt, black pants, black and white shoes and a bandage around his right leg.
Devlin can change from human form to Devlin 11 (a copy of Kevin's original mutation) at will and he gains all of the powers Kevin had in this form. However, he did not inherit Kevin 11,000's ability to absorb matter and energy (confirmed in pop-ups).
Apart from having the same mutation as Kevin 11,000 did at his age, Devlin shared many aspects with Kevin: He met Kenny in the same way Ben met Kevin, after Kenny went off after getting upset with Ben much like how Ben went off after getting upset with Max. Unlike Kevin, Devlin liked his friendship with Kenny. Furthermore, he didn't have the sociopathic tendencies his father had at his age and, in the end, was approached with the same offer to join the team that Ben offered Kevin. Unlike Kevin, who turned the offer down (until Alien Force), Devlin gladly accepted it right away and joined the Tennyson family.