Last chapter she showed up to pick him up from his home... he said he never told her where he lived. It's perfectly understandable that he was already scared of her. Someone he was already scared of showed him that their really strong, it doesn't matter the context at this point it just increass the fear. Not only that, we dont even know if she beat the guy up,shanked him, or just straight up killed him, we just see his feet. Being thankful to her would just be stockholm syndrome at this point.As of yet, she doesn't appear to be seriously dangerous? If I'm gonna be on the side of this wimp, you need to step up the yan.