@Tactical-Ochoa Given that MOA and the other writers were the ones who created him, they probably understand him better than any of us do. And apparently that's the direction which they were going to take Kevin and Charmcaster in the inital sequel Hero Generation. Even when Dwayne McDuffie was brought on he at first wanted to take that same direction with Kevin but then CN mandated Kevin being on Team Tennyson. I don't think that it's completely out of the question that Kevin improves slightly for the better but he would never realistically get close to Ben and Gwen. Perhaps vigilante is the wrong word to use but Kevin doesn't work as a world ending stakes villain as much as he does a personal rival to Ben. Perhaps they're not always purely antagonistical of each other but Kevin works when he challenges the very person whom Ben is.
If I had to redo Alien Force would've actually given him his own arc to parallel the character development which Ben goes through. Perhaps something to do with his past and how he was treated back then . Perhaps there would've been a better way to implement his shattered relationship with his own family. Though rather than going down the path of love and light like Ben does, Kevin would probably take the other road of darkness and anger.