"Slytherins and Hufflepuffs, the two Houses that tended to excel in Potions." - EXACTLY what I think. Because you need to be very precise and hard-working for the subject, don't you? And Ravenclaws are bound to be a little messy, albeit genius. Not to mention Gryffindors.

I am not too sure it's a good idea to have Slughorn (and others?) know about the Cruciatus Curse. As I understand it, it is still reason for expulsion and not only the headmaster can decide to throw students out, as we know from CoS. I love how Rosier bribes him about Snape, though.

Potions Book scribblings - Doesn't this mean Harry should have seen the conversations between Lily and Snape that weren't spells or comments about bezoars? (Love the fact that Lily wrote it.)

Lupin being the one to draw the map fits perfectly.

Very interesting way of narrating a quick, written dialogue, what with only the names added to the actual speech. It's entirely new to me, but I enjoyed reading the convo that way.

"James, Sirius, Remus and Peter had all said the spell over their newest invention, which they had christened the "Marauder's Map"," perhaps, to avoid double wording?

Everything seems to be rather in the open. I sort of expected the whole Death Eater business to be all secretive and stuff. But this is an option, too, and I like it.

No, dear Mum and Dad aren't Death Eaters because they can't find the name 'Voldemort' in their bloody pedigree book or on their precious Tapestry." - LMAO!!!!

Sirius has a cousin who is named like a House-Elf (Sissy)?

Peter's remark on Abraxas not being a Death Eater is genius. At this point, I thought he was already in league with the DEs.