This left me aching. Like Neville, I was practically raised by a grandparent, and devastated when she began to deteriorate towards the end of her life. Neville's anguish at losing yet another family member to mental illness is so very palpable and oppressive and masterfully evoked. I appreciate that you don't make the post-DH world one of happy endings and flowers, but choose to show reality in all of its depressing shades. That Snape, a natural inhabitant of such a world, flickers into Neville's life only seems natural. The pairing makes an extraordinary amount of sense when written like this, and I find myself craving more of your world.
Battered and bruised, pitiless and overconfident, Snape here has never been more himself. It's so very ironic that the moment Neville trusts him -- the moment anyone chooses to trust him, really -- can lead to a kind of downfall. Here, though, you give us a sliver of hope.
Thank you for such a wonderful story. I've recc'd it over at my journal.