Well done. You effectively show both men, in their own ways, as aliens in their own world and yet as being at home, too. I love Viktor's quiet intelligence and Snape's complicated, subtle psyche. There are strong insights into the nature of cultural differences and human similarities -- and into the dynamic of Severus and Harry. I particularly like that paragraph about why they're compelled to act as they do.
Some great lines:
had to have impeccable credentials of loyalty to "the side of Light," whatever that meant. What it really meant was that Viktor spent hours in the company of the most paranoiac witches and wizards in Europe.
His uncle always said cheese would stop a hangover, but Viktor thought his uncle told him a lot of things in order to sound like a charming simple peasant. Haha! Cultural meta; love it.
But perhaps that wasn't a characteristic of Dark wizards, but of honorable men who didn't like to lie but were driven to do whatever it took
A fine story, with all sorts of interesting metaphorical nuances.