How wondrous! I really adored the set-up: the numerous visits, requests for potions, the conversations, and the dinner invitations. Harry's 'buttoning disability' was too funny!
Both your Severus and Harry were masterfully in character: Severus, cold and cutting, yet insecure in his understanding of Harry's motives, and Harry, Gryffindor and Slytherin enough to use both facets of himself to endear himself to and alienate himself from Severus at the same time!
The sexual build-up was delicious, and was not at all stalled by the broken-heart I thought I'd sustained with the visit by the Weasleys to the shop! Hot, sexy, sweet, and adorable (just like our boys)!