Arthur breathed softly as he rested his head on your chest. Well, as softly as a dying man could. Tomorrow the sun may rise, but for all he knows, he may not. He still has things to do. In his mind, he should be doing them right now. But you insisted. At least one night of rest with him before the inevitable.
He made jokes when you asked him for it. Apparently he thought you meant a night of romance. He couldn't bring himself to do that no matter how much he might've wanted to. Physically, because he's not sure he has the energy to do that anymore. And what if he brought you down with him? A cough in the wrong direction and you would be doomed. He couldn't live with that, though he figures it'll only be a matter of time before he's not living at all.
Arthur's steady as they can be breaths halt as it takes him a moment to even be able to breathe in again, but manages to push through with a gasp, then a fit of coughs. He leaned over the edge of the cot, making sure not to get anything on you. He couldn't bear that.