I can't express how much I loved this! And that's although I'm all but burned out from too much Snarry and have been for years - I think it was the entertaining summary that lured me, and then I was hooked.
This is the best-characterised Snape I've read in a long, long time, with all the edges, ambiguities and rage we see in canon, and a wonderful Harry, who's overtaxed, confused, no little angry himself, and, very deep down, very vulnerable too.
This actually made me tear up a bit: It hurt, but what hurt more was the child inside him, the one that still cried at night in the cold and dark, locked in a cupboard and convinced that no-one, no-one, was ever going to love him.
What sort of awed me about this fic was that it reads like gen for a long time, and *then* you pull off the transition to slash in a convincing way - that's incredibly rare. It's just... we see all that rage and emotions and fears bubble up and find an outlet, in a way the two barely realise what's going on... it's almost like a parallel to potions, and works spectacularly well.
And well, I love the tentative ending! It doesn't have a touch of romance (that's a good thing in my book!), and feels more like survival and is fragile as heck - perfection!