After you and her were on a mission you both encounter her father's assasin, in this AU is Bullseye, and after that she wants only to kill him and avenge her father, even if that transforms her in what she hates the most...a killer

When she has the villian in the edge of death You(her closest friend) has to try on convince her that what she is about to do is wrong, and that there must be a better way....will you succed?

"Dont try to stop me" She says furiously at you