Harry Potter’s graphic designers launch collection of art prints from the films - News - Digital Arts - The Marauder's Map
Come on. I think James and Sirius both did that; I think Sirius wanted to prove that he didn't need to be Slytherin to be happy. I can imagine him on his first day poking his head into every compartment of the train with first years and saying "It's ok. That place is fricking awesome. You'll love it" and them all saying "how long have you been going?" And him saying: "who me? Never even been. But trust me - I know what I'm talking about"