My brother accidentally got seriously hurt in a pub brawl

There was a brawl outside a pub between two groups and my brother was knocked out as he was punched from the back. He now has a NOE fracture and is going in for surgery today. We checked the CCTV footage, my brother was not involved in the brawl at all until he got punched. After that his friends retaliated against the person who punched my brother.

Should my brother press charges against the perpetrator? And if so, will his friends get into trouble for retaliating? No one else was seriously injured.