Merlin seemed to start breathing again. There wasn't much more shown in the way of relief, but he kept smiling slightly all the same. After a minute he offered a whispered, "Thank you." Because that had really been all he needed to hear. For all their arguments, at least he knew Arthur did consider him a friend regardless to how they acted sometimes.
"I'm going to run you a bath, and get your bed ready..." Merlin commented absently, disappearing off into the other rooms. The sound of the bath started, and then continued -- and kept going. Some time had passed, and Merlin didn't come back out of the bath room. The water just kept running.
Merlin had turned on the hot water, sat down beside the bath, and put his head down for just a second. The room warmed up, his eyes closed long enough for him to finally drift to sleep.