So, when he feels the bladed end of Loki's staff leave his chest he can feel the pull of blood as it fills his lungs and the wet stuttering sound it makes when he inhales. Liquid being there isn't new, but the pain in that area of his body is.
He had laughed when he was told he was so unassuming and the least threatening of all the agents SHEILD could have sent. He knows, however, that appearances are deceiving.
His eye sight is growing grey at the edges and he knows he's headed towards unconsciousness but even as his heart slows to where it's barely detectable, he'll awaken when his energy isn't being spent healing. Explaining these phenomena to Fury isn't going to be fun and the man is going to become even more paranoid, but he is a child of Death and death doesn't come so easily for them.
