The Weakest Becomes The Strongest
Weak. Useless. Dead weight. That's what she was in all of Konoha 12's eyes. Well , minus Hinata , Yamato and Sai. But yeah , other than that no one cared and that made her an empty shell. That empty shell was a perfect weapon for Danzo and he offered her to join ROOT ANBU. Having no other job than being hospital head...