Fable's fanboy is the one who introduced Misaki into this mess, don't get disillusioned because he's fantasizing about MC. MC killed doctors and CEOs, he's not a good guy either. He just wanted to repay the kindness of someone who reached out a helping hand, and probably has feelings he can't understand (like/love) towards her. That's being principled, and he couldn't have survived without principles and discipline.
Don't forget the MC is a bad guy that took out an another bad guy. We've only seen him take out bad guys so far, but that doesn't mean he's good (knowing his past, we know he's bad).