We figured it out!

[Amanda Lewanski]

No: HPFGUIDX 4231

Yay! My one and only non-virtual friend who's read the Potter books is
over here tonight, and she has (I think) solved the question of why
nobody else noticed "Peter Pettigrew" on the Marauder's Map.

1. Me: even if Scabbers were at Hogwarts with Percy, too, and thus
within the time that Fred and George were using the Map, they'd have
been unlikely to check their dormitory for lurking dangers. They were
checking hallways and offices and such. They didn't have to check for
people who might catch them sneaking around their own rooms.

2. Her (Anne, by the way): even if Fred and George did, for some reason,
see "Peter Pettigrew" someplace on the map, they would not know who he
was. We've already discussed the general non-informed status of the
children about the Voldemort years. Wizard parents were having to
explain to their kids who Sirius Black was; why would anyone have known
the name of his supposed victim? (before Harry and company learn about
it in book 3).

3. Me: for the same reason Fred and George probably never noticed him,
Harry probably wouldn't have. You simply don't check for lurking nasty
maintenance men or Snapes in your own rooms. And Scabbers spent most of
the time in book 3 hiding in their room, because Crookshanks was after
him and it was the only (reasonably) safe place. Lupin only saw him on
the map when he was out with Ron after they'd found him at Hagrid's.

So, have we solved this? I was delighted when she pointed out such an
obvious, overlooked thing, that the *users* of the map would not have
recognized the name.

--Amanda