Hmmm there's a lot that could be fleshed out here so I'll just start with the ones that came to me immediately.
How did she get out of the evil organization that was involved in killing and theft?
Why does she never have a team or a sensei, even when she passes the Chuunin exams at Konoha (which from what I recall from the series involved teams)?
Does she have any other friends besides Koga and Shirahime?