There is quite a gap between what the houses are stated to be and what they're actually portrayed as in the books. Like, JKR tells us that the Slytherins aren't all bad and that being a Slytherin doesn't meant hat you're evil, but she never actually shows that (which I tend to view as her own biases coming through.) I think you mentioned somewhere that Marco's a good example of a 'heroic' Slytherin, so he's basically a lot like what I imagine many Slytherins would be like, if they weren't being cast as the villains because JKR doesn't like cunning and ambitious people so much.

I can definitely see that! And I could imagine that with his home life, knowledge could have been something of a friend - since books are something that wouldn't neglect or abuse him. It is sad, and yet so incredibly amusing XD