Okay the rough idea I have going is Steve as an enhanced vampire hunter who is less interested in hunting vampires and more in catching murderers who happen to be vampires.
See: scene with Erksine where he explains he doesn't like bullies. He's not here to discriminate. He wants to stop bad guys. He just happens to specialize in vampire bad guys.
Admittedly this AU is really overwhelming for me so if you guys can help me figure out how to fit Steve in that would be wonderful because otherwise I'll have to opt out. :<