That's fair! As far as the middle nickname go, like Mayhem or Unbreakable, I think it'd make sense to pick one that goes with his personnalitynor style. Like if he's the kind of guy that just takes hit after hit but just keep going no matter how the odds are againstvhim, then Unbreakable could fit. Or if he's known for his fast, powerful and precise punches then Sniper is good.
But for the actual name, I have no clue haha!