Was any extensive history ever given on Fonzie and why everyone was so afraid of him? I get that he was in a gang and such, and I understand why the nerds were afraid of him, but he could walk into a gang, or basically anyone, and they feared him. Had he beat up 10 guys at once before or something in his gang days?

he had been the leader of the Falcons and they used to be one of the toughest gangs in the city, apparently the Fonz had been a very formidable fighter and had a reputation as such.