Brien- His son had attacked him, in his own home, the minute he had arrived; throwing Sheridan's name in his face accusing him of unspeakable things. He wasn't just hitting him he was trying to kill him or so it seemed to Brien. He wouldn't even try to talk to his son. He wasn't going to listen to anything.
Thank god Dionne' came in when she did. The last thing he wanted to do was hurt his son.
When Dionne' asked him what was going on and why, he could honestly say that he didn't know what was wrong with Brian.