The problem with headbutts was that they came down to who was the most prepared, but also to who had the harder head. The back of David's skull hit the wall behind him with an ugly crack that sent stars spinning behind his eyelids, but the other man staggered backwards, swearing and holding a hand to his forehead.
"You're telling me you'd have left us alone if you'd seen a number on her arm?" David inquired, but his calm cracked by the end, rarely-heard anger in his voice. He was a pacifist by nature, liked to see everybody getting along, liked helping people. He'd fight when he had to, could understand opposing causes, but tended to view most conflicts as regrettable, held back when possible because he could understand where everyone was coming from.
The one thing David could not stand was pure, sadistic malice, even in its most brutish form. People getting mad at him, fine, people being afraid of mutants, fine, but what the giant idiot was doing to Arla? There were some things he would not tolerate. He kicked the friend back, sent him tumbling towards the crowd which obligingly gasped and did nothing else, and moved up to grab Geoff hard by the collar.
"I'm giving you a warning," David said, voice hard. "Get off of her, go away. Now."