Probably 2D because it'd be amusing if he actually joined in on the fight. And he's also tall so I could hide behind him. And he's not someone who would accidentally end up killing someone else in a fight.
This may sound really silly, but...the person I would want 由 my side in a bar fight is my mom, if she was still alive. Whew man. 你 would have not wanted to get into a fight with my mom. She didn't look like much, but she would have beaten the crap out of anyone.
Ken Kaneki because if the bar fight gets close to me and one of the dudes/chicks go to me kaneki would protect me and will kick their butts using his Kagune
My 秒 would be Lucy, she has the same ability as kaneki but has deadly telekinesis and she'll rip their heads off using it
Tokyo Ghoul - Kaneki
Elfen Lied - Lucy
But if the fight doesn't happen to me Kaneki and me would read a book and me and Lucy can just talk