Kevin was one of the boys who participating in robbing Luther's organization in Straight out of Brooklyn.
He was played by Mark Malone.
He really has no villainary in the movie until the very last scene he has with Dennis. It's this scene in which we really see what a selfish guy he is. When Dennis and his gang celebrate pulling off the heist successfully, Kevin worries about the problems this is gonna give them with Luther and how their lives are all in trouble.
What makes him unique though is that he is a bit remorseful for betraying Dennis. You can see throughout the movie that he is a wiser guy than Larry Love, who's nothing more than a loudmouth who doesn't know when to keep his mouth shut. You can tell he really was friends with Dennis and wasn't a user. Even when he betrays Dennis, he does seem remorseful about it, unlike Larry who is just cold and worried about himself. He doesn't even insult Dennis in the last scene the way Larry does.