The Marauder's Map follows quickly after Harry's interview with Lupin, and the contrast is interesting: responsible Harry, seeking knowledge that will protect him and make him stronger against the things haunting his waking life, getting direction from the most fatherly figure in his life right now; while reckless Harry seeks a different sort of knowledge, the sort to distract him from those haunting things, but put him at risk from them as well..and, as for the person or persons responsible for each source of knowledge, SPOILERs are lurking there, so we'll wait. But Jenna has some interesting questions about the map:
How did Fred and George ever figure out how to work it? (I like to imagine they wrote things that Filch would have found threatening on the paper and activated the spell that way, later switching to speaking the spell to save time.)
Did Messrs. Moony, Wormtail, Padfoot, and Prongs use the exact same phrasing? (I doubt it, the map seems very aware...maybe it recognizes kindred spirits in how they attempt to figure out what it does. Maybe they just said 'map' and 'done' - Fred and George like to be showy.)
I'm not sure how I feel about the concept of a spell of concealment within a 'single, living soul' it's an interesting concept, but why couldn't James himself have been the 'secret keeper' - then there would have been no trouble. He could reveal it to those he trusted, and he'd be certain not to betray himself or his family? Why not? Anybody know? But I'm with Jenna..I'm determined "not to question the believability of a scene in which the Minister of Magic and Professor McGonagall gossip wiht Hagrid and a barmaid." Didn't the Minister throw Hagrid in prison with no evidence just last year? Sometimes it's good to hold a bit of a grudge, Hagrid. Challenge the Minister to change his ways before you'll be willing to drink and laugh with him at bars!