He.

His soul was slowly dieing. His hands did not tremble anymore. He used to be amused by abnormal silly things. Like the color of her sandals, or the smell of Canadian maple syrup in the mornings. Everything that provoked him in any way, slowly went away with the tiny specs of his engulfed soul. His reflects were sharpened, though he did not care anymore. He was a machine, enough to take down anyone with speech or force. He knew how to disappear, how to be evaded, to be confused for. He knew Morse code, the 10 code, and every other word in every other language. In numerical terms, he did not exist.
Alone, he was always enlightened. With books and internet he learned about everything he needed to know to pursue. With her, he was a half act. Extirpated from the majority of his soul, he could not fulfill his social commandments completely. He searched for her in desperate moments where he hung by a thread... for salvation, in a twisted way, to forget. He used her to feel alive, young again...