The spindly thing is intentional. I mean for her to be both intelligent and athletic but still be a realistic member of the B-Team. Thus my original thought on that was 'she did it out of boredom'. I made it a bit more sad than that though. She joined up during a very damaged mental state that was elongated by locking herself away from everyone else so really, it's meant to not make sense. I mean, try locking yourself away with nothing but some random paintings and abstract sculptures for four years and see how sound your decision making skills become. I also believe that she can realistically stay with the B-Team seeing as how that is the way she reintegrates herself into society. 

Even though I am being a bit defensive about it, I would definitely be willing to make some minor changes to it to have it be more believable if you are willing to help me out in some small way. I'm a bit exhausted from writing that much so my brain has sort of melted.

EDIT: Also thanks for complimenting the shield thing, I enjoyed the idea myself ^^