Anythign can happen, but I'd lean character chooses us. Case in point: made my then-new Grav/Dark Troller Trash Ghost. Somewhere around level 14 or maybe 20 something felt odd, so I checked back and hey yeah, I had the same power combo on another troller I had taken to like 46 some months ago, but never felt right about - so much so that I had even forgotten he existed (and I still can't recall his name right now, ha ha!). He'd never fired me up much, but had only reached that level due to inertia, "well, this is my new one right now, so I guess I'll keep playing him." I ended up cannibalizing from him a bit to kit-out the new troller, which is something I almost never do. He still sits at 46 or whatever, meanwhile Trash Ghost is in my sig lists of 50s and has, I think 20+ vet levels. I still pull him out, too.