I read this last night, stayed up WAY past my bedtime to do so, and enjoyed it very much. Although I will say that I was thinking up horrible things to do to you if you killed Lily Eileen, as the pastiche trope looked like you meant to do.
Snape makes a fetching Scarlett, it's true. And Harry makes a sad, tragic sort of Rhett, but once he's had enough torment, he roughens up nicely indeed. And I loved the idea of him deciding to go and turn himself into someone worthy of Snape, and then learning that he's so far overshot the mark that Snape's not worthy of HIM.