They are both strangers in a strange land, aren't they? Snape has been the odd man out since childhood, never fitting in anywhere, his one 'safe' place in the form of Lily Evans nothing more than illusion. Viktor Krum is introduced to us as already a celebrity - a foreign quidditch phenom already distanced by hero-worship from his classmates and the Hogwarts students he's thrown among. Ron's mocking of Viktor's accent is a great tell, trying to bring the object of his admiration down to size and clueless that he's being offensive.
I love that your Viktor is so perceptive, even if sometimes culturally at sea, he can nevertheless zero in on what's at the heart of most matters. His instictive comprehension of Snape is wonderful, and one really feels for Harry in his thwarted attempts to give olive branches to Severus Snape, how Viktor understands their dynamic so easily: Harry Potter couldn't possibly understand how much Snape stood to lose if they reconciled. To have to see the person who had witnessed him kill, witnessed him nearly die—who had seen his lowest moments, including Harry's own mother's death—it was not something Snape could bear.
Viktor knew something about how survivors could be so tough that they were brittle. He also understood why Harry would pursue Snape anyway. It was nothing either of them could help. Harry must know why Snape avoided him and Snape must know why Harry sought reconciliation, yet they could not stop. Someday they would be old men like his uncles, almost whole, almost recovered, but not quite.
And this: Harry would make an excellent Dark wizard, himself, Viktor thought. He had the sophistry to deceive without lying, which was Snape's stock in trade. Snape never told anyone an outright lie if he could help 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 to win. It was unfortunate that Viktor found himself between them. Brilliant insights, both.
Severus, at first, we see only through Harry's longing and Ron's peevish dudgeon on his friend's behalf, and then as a distant and respected presence in Viktor's work life. The view we get of him after Viktor begins to work with him more closely is heartbreaking. We know it's personal, this quest to prove that mistreatment as a child begets the inclination to Darkness. Not, perhaps, to justify himself or Tom Riddle, but in an attempt to stop it happening again. And like anything Severus begins, it becomes obsession; only this time he has Viktor there, who understands and soften the drive. Again his instinctive understanding leads to great insight:
Snape was beginning to look tired.
"Where can we get a cup of tea?" Viktor asked the librarian. There was a café right in the library building. Snape looked startled. "I'm sorry, Professor, I'm a bit hungry," Viktor said, trying to spare his supervisor's easily bruised feelings.
Snape was a bit fragile after all he'd been through, and could become exceedingly grumpy when he felt ill. Even though he was still a young man, he would push himself to work hard enough to make himself sick. One could never say, "Are you all right, Professor?" because he was liable to growl and snap.
The way they come together in the end was just lovely, awkward and hot, all of Severus's insecurities for once dispensed with without argument, their superficial cultural differences only adding to the pleasure, their deep cultural similarities bringing them closer.
As you can probably tell by all of this flail, I loved this - written with such beautiful restraint and terrific characterizations. This is one is one of the best of the fest, in my opinion, and I will be rec-ing it later. :-)