Part 1, because I do go on
I read this story with the mist hanging still and silent outside my living room window and deer picking their way across the grass. I've been playing medieval music for the last few hours, because it fits the midday hush. As does this extraordinarily beautiful story. The atmosphere here is wonderful: cold and bracing, lonely and wild, exactly the conditions in which I'd expect to find a Snape who's gone to ground. The quietness of the story itself is uncanny, because it's exactly what I'm in the mood for. I adore your descriptions of Snape, his harsh, stooped angles that straighten up in Harry's presence, that inner sense of a vanquished self, remote from life. His preternatural calm. I love how you depict this as a refusal to feel, which is such a mixed blessing. It allows him to live at peace - perhaps to live at all - but it's the peace of a cold grate after the fire's gone out.
I've said elsewhere that I tend to focus on Snape more than Harry in fics, but not this time around. Because your Harry makes so much sense to me. His reasons, his urgency, his lack of anything meaningful in his life, his good intentions - it's so recognizably him, and yet it's tempered with regret, with the experience of having done the right thing only to find he doesn't really know himself at all. He's both brash and humble, but the way he reacts to the landscape and to Snape - not to mention the fact that he's being carrying this yearning around for 20 years, unfulfilled - really strikes a chord with me. I can see why Snape doesn't throw him out.
The way their conversations circle and feint, dying off when Snape withdraws, are hypnotic. The whole psychological mood is weirdly and beautifully balanced. I spent most of the fic unsure whether I wanted Snape to agree to go back. Because in certain ways the isolation suits him, even if the loneliness has emptied him out. And the things Harry tries to tempt him with aren't really the things Snape needs.
Other things I loved: Harry's flights on the outdated broom. The line: every time he thought of them it was like a moment of true life. Snape's comments about Harry being the centre of the universe. Because of course Harry was. I sat up straight when I read that, especially when he repeated it. Snape saying, "I thought I would never forget, but it fades." (Oh, my heart!) The phrase: the icy square of savage beauty beyond the window pane. This is a line that somehow utterly belongs in a Snape's fic, and the fact that it's Harry who perceives it just makes it that much more perfect. Harry laughing like a maniac when he crashes on Snape's lawn. Quidditch as sexual innuendo! (And Harry not knowing until now!)
"I don't know why you're not insane," said Harry.
"I don't know why you think I'm not," said Snape. I adore this parry and thrust, the intelligence, the evasiveness.
And I'm so glad you have Snape say this: "You think you can bring me out of my shell with hate? Don't you think, Potter, that hate is probably something I have had my life's share of?" Because it gives Snape his due and allows him to grow up. While Harry, even knowing he's on the right track, knowing he's forced Snape to feel, doesn't stop and listen to what he's just said. Snape's just opened his fist and shown Harry what's been clutched tight in his heart, and Harry misses it.