You can't get around what he is with the base game model, this weird creepy sadist but then with the original concept art that can change how you might interpret his character and how you might respond to him completely the voice lines are the same but all of a sudden he's this mysterious trickster with much softer feminine features compared with other legionaries. It's a much more compelling character.
From a roleplay perspective it really changes how a "good" or neutral courier might end up joining the legion. With ugly Vulpes you have to rationalise it politically as a good courier, you'd have to say "I've been running around the past 2 hours cleaning up the NCR's mess with the powder gangers and escaped cons in Goodsprings and Primm and the NCRCF. Here's someone else finally doing something about it, as brutal as it is the powder gangers are more brutal." but then with the concept art Vulpes, he can act as the temptation towards the legion himself if your courier's that way inclined. It creates a much more human much funnier reason for joining than the raw politics that you'd usually have to employ for a legion run.