He’s taken the hearing aids out, not because he feels comfortable enough but because his whole head is starting to ache, and he’s not expecting anyone around, anyway. He’s milling around one of the more secluded areas of SHIELD - the little nooks and crannies that most people don’t seem to know about.
Without the aids, his hearing is only about seventy percent, and he doesn’t catch the footsteps until he sees them.
"What d’you want?" He’s speaking just a little bit too loud. One hand rubs at the back of his neck. "I’m busy."
He is most definitely not busy.