Seamus had been about to make some easy joke about the two of them and their wild oats, but then the mood snapped. Though his eyes widened, Seamus didn't panic. This had happened before. Instead, he made a quick gesture to the few customers who'd been alarmed by Dean's outburst that it was under control. His pulse was beginning to pound, a familiar adrenaline filtering through his system.
"Okay, Dean, I'm sorry. I won't." He couldn't really see the difference between joking about Jess's crush on him and joking about fake dating her, but that didn't matter. There was obviously a difference to Dean. And he was genuinely sorry, for triggering Dean if nothing else. He held up his hands in a gesture of truce, showing he still trusted Dean not to really hurt him, showing that he didn't want to fight. "The flat's open." The flat was always open to Dean, twenty-four seven, but it was more tactful a prompt than saying 'do you need to get out of here?'. He could give Dean some time to calm down, then get one of the kitchen staff to cover for him for a few minutes.