I really liked this story :) You did a great job with Snape's voice and how he didn't feel like he had a reason for living or caring until Harry kissed him. Maybe Snape had some feelings for Harry that he hadn't let on?
I also like how Harry gave Snape a free choice at the end. It showed in the wording you used "Harry found himself shaking a bit because he didn't know what Snape would decide" Harry really did care enough to set Snape free and see if he came back on his own. Lovely ^_^
Oh I hope you don't mind, but there's a spelling error here I think: If Greybeard hopes to get a reaction out of Leary, Harry doesn't see it -- the Minister continues taking his notes undisturbed. you might mean "Greyback" and not "Greybeard"?