"Punching a mugger in the face is good stress relief." Granted, her first act as a vigilante mean saving her sister's wedding from being ruined and then it was an act of defiance, but now Kate does it for much better and less selfish reasons.

But she can't deny sometimes putting an arrow in someone's butt doesn't feel good. Plus when the adults seem too busy to save the world, it's up to her and the gang.