He was still alive when Narcissa arrived, though weaker with every breath. He was not a stranger to death, had inflicted it on others enough times to know it was not pleasant. He knew he was dying, and as he felt Narcissa at his side, he felt the last pieces of himself go.
He did not move, or talk, or touch her a final time. He did not even have the energy to look up at her. Instead he just felt his life slip away, one thought filling his mind as he died.