Xavier's one of those characters who's still manic from his traumatic backstory.
I'm imagining raiders attacked his village when he was a child, threw him alive into a pit with all of the dead bodies. He did what he had to to survive in that pit, and when he crawled his way back out, he stabbed the leader of the bandits in the back.
You can't see Brock's eyes under the helmet, and Eric just seems too smug. They're my bets.