Yay long plotty Snack! I enjoyed it very much! I admit I usually like my Snack more hate-flavoured but Sirius's change of attitude was believable and you kept Snape sharp-tongued and wary and unwilling to open up. Plus, they kept delightfully snarking at each other. Well, delightfully to me, though I think they rather enjoyed it too. ;)
Also, yay for Sirius-back-from-the-Veil AU! It was great how you used so many canon facts and events from HBP and DH in an AU way, incorporating them into the story. I loved what I assumed to be little meta moments like what the locket Horcrux said about Dumbledore and Sirius's throwaway comment about Hagrid's conception, heh. And something else I'm now forgetting - damn, I should have taken notes! When Sirius found out about Regulus I was so moved. Oh, Regulus. <3 If only that could have happened in canon! And Snape killing Nagini - that was a wonderful, gleeful moment. :D