He is unarmored and likely to be weaponless, so a few ranged attacks should easily dispatch him.
If a charm spell of the correct magnitude (varies depending on level) is used, to the point where he is no longer hostile, it is possible to speak with him.
- If the Hero is wearing the Gray Cowl of Nocturnal, he will greet them in the same way that members of the Thieves Guild and highwaymen would: "As I live and breathe! The Gray Fox! 'Tis an honor."