Abraxas is probably my favorite pureblood character, and I enjoy stories like this, that explore the psychology of his privilege and the ins and outs of pureblood politics. You do a fine job with young, promising, but still callow (and always prickly) Severus. As Pauraque says above, there are many interesting layers with Lucius, too.
But my very favorite section is the Poppy cameo. What an excellent job you do with her; she's so fully characterized in just her brief moment on the stage. She does the Slytherins proud.
Dumbledore is touched in the head, he's not completely insane. Haha! Great insight.