Archer saw 'eccentric' written all over Bryant, in big capital letters. When O'Brien moved past him and engaged the doctor in conversation, Archer had been watching like a hawk from his place at the doorway, and this was what he took away from it:
1) Dr. Bryant O'Neill was a generally anxious individual. Somehow, the conditions of his stay -- the storm, overhearing the scream, some other factors that Archer was as yet unaware of -- were only heightening his anxiety. 2) Dr. Bryant O'Neill was not a malicious person. If he was, he was hiding it extremely well. He'd been courteous even in the face of whatever was making him so anxious. He'd been cautious but polite in the way he'd examined Archer's badge and responded to O'Brien in conversation. 3) Dr. Bryant O'Neill was fucking oblivious to the fact that his room felt like a sauna.
Okay, so maybe it wasn't that bad. But O'Brien was spared Archer's usual glare when it came to loosening his tie because as Archer took two steps into the room, he felt the warmth that much more keenly. Maybe that was because he was in a wet trenchcoat with damp hair, because he and his partner had just come in out of the rain... but this place was uncomfortably warm. It was the sort of thing a guy should notice. O'Neill hadn't, he honestly hadn't until O'Brien pointed out the obvious. Archer tentatively put this down to a combination of the absent-minded professor vibe the guy gave off and the strain he was under with the 911 call and... whatever else.
Pulling out his notebook, Archer's eyes darted over to O'Brien crossing the room before settling back on Bryant between them, looking like a deer-in-headlights. "Doctor," he began, flipping through pages deliberately before turning to the first blank one, giving the guy a chance to not be under scrutiny for a few seconds, "What prompted you to call 911? Can you walk me through that?" This was tame language from Archer, who was beginning to mentally rearrange his priority list. He and O'Brien would have to split up, and unless O'Neill was a sudden font of knowledge beyond what he'd told the 911 operator...? Archer and O'Brien would be splitting up sooner rather than later. The captain silently sorted through the interviews and search details he wanted to cover as he waited for Bryant to answer.