Dabi, real name Touya Todoroki, is the eldest son of the Pro Hero Endeavor, driven insane due to his neglectful and selfish actions, and becoming a villain to enact revenge. He became affiliated with the League of Villains and later one of the nine lieutenants of the Paranormal Liberation Front. A 'Quirk' is a superpower, quirks are physical and not magical. People only have one quirk unless their quirk allows them to take another or whatnot(like All for One for example).