Fred and George stumbled upon the Marauder's map in their first year. They passed it on to Harry while in their fifth year. Also note that, while talking to Harry on the train, Ron described Scabbers as being "Percy's old rat".

Hence, we can safely assume that the twins had the Marauder's Map for about five years. How could they not see Peter Pettigrew on the map, with Percy for first two years and with Ron for the next three years?

How come Harry didn't see Peter? How was Lupin the only one able to see Peter on the map?

  • 21
    Interesting question, think it's something that was allowed just for the sake of the story, but he shouldve showed up on the map earlier. Extra questions this one brings to my mind: 1. was Percy's rat always Peter, or was there a rat called scabbers before and did Peter take his place along the way. 2. If Peter was Percy's rat, and he was undercover for all these years. Why would he be Percy's rat to begin with? Before Harry's friendship with Ron the Weasleys were of no significant value for Death Eaters. Good thing you asked this question, I always felt this part of the story needed digging. Commented Feb 19, 2012 at 10:59
  • 17
    @HansWassink Sirius has a theory with respect to this. Remember he tells Harry, Ron and Hermione that Pettigrew just wanted to find a wizards family to keep up with news with the magical world, and that he was so "lucky" that he ended up with a family that would eventually include Harry Potter's best pal at school.
    – Janoma
    Commented Feb 19, 2012 at 13:36
  • 8
    How do you know Lupin was the only one ABLE to see Peter? What if he was the only one to NOTICE peter?
    – Möoz
    Commented Mar 20, 2014 at 21:08
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    Didn't scabbers sleep in Ron's bed every night? That would have looked odd on the map... maybe the brothers didn't want to get into an awkward situation.
    – Daft
    Commented Feb 26, 2015 at 16:31
  • 3
    I'm confused by the last line of the question. I thought Harry actually noticed Peter Pettigrew. This may be recollecting the movie version of events, but I'm pretty certain Harry comments on the map being "broken" to Lupin because it shows someone he knows to be dead. This triggers Lupin to re-think his positions concerning Peter and Sirius, which eventually leads him to the correct conclusion.
    – Ellesedil
    Commented Mar 10, 2016 at 8:20

14 Answers 14


Rowling was asked this question about Fred and George:


Why didn't Fred and George notice Peter Pettigrew on the Marauder's Map before ("Prisoner of Azkaban")?

It would not have mattered if they had. Unless somebody was very familiar with the story of Sirius Black (and after all, Sirius was not Mr. and Mrs. Weasley's best friend – indeed, they never knew him until after he escaped from Azkaban), Fred and George would be unlikely to know or remember that Peter Pettigrew was the person Sirius had (supposedly) murdered. Even if Fred and George HAD heard the story at some point, why would they assume that the 'Peter Pettigrew' they occasionally saw moving around the map was, in fact, the man murdered years before?

Fred and George used the map for their own mischief-making, so they concentrated, naturally enough, on those portions of the map where they were planning their next misdeeds. And finally, you must not forget that hundreds of little dots are moving around this map at any given time… Fred and George did not know everyone in school by name, so a single unfamiliar name was unlikely to stand out.

  • 61
    I realize that she gets to make the rules, but this is a pretty poor explanation, honestly. Surely at some point Fred and George would have looked around Gryffindor tower and seen Peter Pettigrew, a boy who didn't belong, just a floor above or below them in the middle of the night (depending on when they looked.) Commented Oct 4, 2014 at 0:58
  • 14
    @JasonPatterson: True that. I'd go so far as to say that Peter Pettigrew spent a lot of the time on the map right next to Ronald Weasly. Stupid explanation. At least the movie tried to correct it by showing Harry noticing him.
    – Tushar Raj
    Commented Apr 8, 2015 at 13:08
  • 18
  • 7
    @JasonPatterson Why would they be looking at the Gryffindor dorm? The twins only used the map to plan their wild hijinks, which I imagine mainly involved sneaking into places they weren't allowed, or access secret areas (none of which were in the dormitory). Presumably the novelty of just watching people move about was long exhausted after their first year.
    – DavidS
    Commented Jul 27, 2017 at 9:00
  • 5
    @BolteAltamont: To be fair though, this isn't a map that tells you where you need to go. F&G aren't looking for directions, so there's less reason to look at your starting point. There's a good argument to be made that they used the map to safely enter places they weren't allowed to be; which would then not apply to their own private quarters as they are allowed to be there.
    – Flater
    Commented Jul 28, 2017 at 7:29

This is purely conjecture, but it's entirely possible that the Marauders placed some extra protection on the Map in case it were to fall into the wrong hands -- a "hide-the-Marauders" function, if you will. If you think about it, this makes sense -- for, as we know, it did fall into the wrong hands, and they wouldn't want anyone to know about their monthly excursions or any of their other Invisibility Cloak adventures. Moreover, they probably only would have wanted it to be a temporary function, so that they might be able to find each other if necessary.

So let's say that there was this hide-the-Marauders function, and it was enabled when Filch confiscated it. Fast forward to Fred and George discovering it. They don't notice anything wrong with it, of course, because none of the Marauders are supposed to be at Hogwarts...until the year in which Lupin arrives. Still, it's clear they don't use the Map much anymore by this point -- they've outgrown it, and they're even passing it on to Harry. Nobody notices that the new Defense Against the Dark Arts teacher is never on the Map -- and why would they? Both Harry and the Weasley twins probably like Lupin, so he's not somebody they'd be watching out for; plus, it's probably a lot harder to notice someone's absence from the Map than someone's presence on it (especially, regarding the case in point, if that someone shares a common room with you).

Then Lupin confiscates the Map, and what does he do with it? He's smart -- he uses it to watch out for Harry, as we know he did on the day of Buckbeak's execution; he must also want to use it to watch out for Sirius Black, who has already managed to break into Hogwarts once. So he disables the hide-the-Marauders function, but by now Pettigrew (as Scabbers) is hiding out at Hagrid's out of fear, and no longer living in the Gryffindor Common Room. Because Lupin isn't focusing on Hagrid's hut -- why would he? -- he doesn't notice his old school friend until one night, when Harry, Ron, and Hermione sneak out to see Hagrid...

Again, based purely on conjecture and circumstantial evidence, but that's how I've always justified it in my mind.

  • 10
    I love this theory, as you say, conjecture, but the reality is that there are some ticky-tacky issues in any series, I read an interview with George RR Martin where he expresses great concern for the mental well-being of the folks who send him letters about similar tiny issues that Martin himself stated he was not aware of in his books. That said, you've come up with a very creative answer that would fit well in the storyline, well played.
    – the_SJC
    Commented Sep 15, 2017 at 19:43
  • This is the only theory that actually could work. Of course the Marauders must have also put in a "Hide the Dark Lord" function -- as the twins never spotted Voldemort/Riddle riding around on Quirrell. ;) Commented Feb 8, 2018 at 7:10
  • @BrockAdams Or they simply had no interest in tailing teachers..? I mean she points out that it was for mischief making. Okay yes they enchant snowballs to hit Quirrell ironically in the back of the head (iirc) but they hardly needed the map for that.
    – Pryftan
    Commented May 27, 2018 at 20:05
  • 1
    @Pryftan, when you are breaking school rules, like the Marauders (and Weasley twins), you pay extra super special attention to where the teachers are and what they're doing. The whole point is not to get caught by said teachers. Commented May 27, 2018 at 20:47
  • 3
    This theory wouldn't even need Lupin to disable the hide-the-Marauders function. It'd be perfectly plausible for the map to hide Marauders from everyone except other Marauders. (Does anyone except Lupin ever see the Peter Pettigrew dot on the map in PoA?)
    – Rand al'Thor
    Commented Jun 3, 2021 at 13:18

I always thought that Fred and George (and later, Harry), never used the map while Percy (and later, Ron) was holding Scabbers, which probably happened only during bedtime. At any other time, the name of Peter Pettigrew (for example, at the Great Hall), would have been insignificant to those who didn't know him.

Also, remember that the map showed "hundreds of tiny dots with labels", so, for all Fred, George and Harry knew, Pettigrew could have been just another regular student they didn't know, and who happened to be nearby. This is not shown properly in the movies, where the dots and labels in the maps are larger than what's described in the books (for obvious reasons, though).

  • 4
    Considering how everyone knew who Sirius Black was, I doubt that a wizard family like the Weasleys wouldn't know who Peter Pettigrew is.. Commented Feb 19, 2012 at 17:40
  • 7
    Maybe Percy, Charlie and Bill, but not the twins, who were younger. Anyway, it seems like Arthur and Molly don't let their kids know too much, especially stuff that is "too dark".
    – Janoma
    Commented Feb 19, 2012 at 17:46
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    Real life analogy: I could name a handful of serial killers, but couldn't tell you any of his victims' names. I bet most people are similar.
    – dlanod
    Commented Feb 19, 2012 at 20:16
  • 2
    Also, most people would remember that Sirius was convicted for murdering 13 muggles, since they associated this with his alleged support of Voldemort. The death of a wizard could have been considered secondary and forgotten by the masses.
    – Janoma
    Commented Mar 18, 2012 at 15:23
  • 12 muggles, sorry.
    – Janoma
    Commented Mar 19, 2012 at 2:24

I think that the answer to this question would be that Fred and George's knowledge of the castle was so complete that they were only using the map intermittently, and only to find out where Filch and the teachers were.

As such, they were unlikely to look in Gryffindor Tower, where Scabbers was most of the time.

The events that took place when Harry was handed the Marauder's map went like:

  1. Fred and George gave Harry the map;
  2. When Scabbers disappeared and hid out at Hagrid's, and;
  3. When Professor Lupin confiscated the map.

I think these events were all close enough together such that it is not unreasonable to think that Harry may not have looked up his dot when he was with Ron and Scabbers in Gryffindor Tower.

Lupin probably did not use the map after he confiscated it, until the time in the book when he suspected Harry Ron and Hermione would attempt to visit Hagrid.

So I think it is believable that Peter went unnoticed until Lupin used the map to track Harry, and saw Peter on the map at Hagrid's.

  • Good point about scabbers hiding. I forgot about that.
    – Tushar Raj
    Commented Apr 8, 2015 at 13:12

Peter was not shown because the map knows the viewer's intention and only shows things of significance.

Although JKR has answered the question, perhaps we can postulate something else based on the books, as seemingly we clearly see that at least one time Scabbers did not always appear on the map:

“Ron, I don’t believe it — it’s Scabbers!” Ron gaped at her. “What are you talking about?” Hermione carried the milk jug over to the table and turned it upside down. With a frantic squeak, and much scrambling to get back inside, Scabbers the rat came sliding out onto the table. “Scabbers!” said Ron blankly. “Scabbers, what are you doing here?”

And then here:

“The number of times I saw James disappearing under it…” said Lupin, waving an impatient hand again. “The point is, even if you’re wearing an Invisibility Cloak, you still show up on the Marauder’s Map. I watched you cross the grounds and enter Hagrid’s hut. Twenty minutes later, you left Hagrid, and set off back toward the castle. But you were now accompanied by somebody else.”

Now, if Scabbers was hiding in Hagrid's hut, he should have always been visible! So why did Lupin not see him in Hagrid's hut the whole time? There's simply no way to answer there were too many dots, clearly, the only dots in Hagrid's hut at the time were Hagrid's and Pettigrew's!

We also see that the viewer isn't normally on the map:

What did he have to do? He pulled out the map again and saw to his astonishment, that a new ink figure had appeared upon it, labeled ‘Harry Potter’.

This clearly implies that Harry himself had not been on the map before! (If he was, the book should have said "he watched in astonishment as his dot grew bigger". Not the best proof, but supportive.)

However there are three facts about the map that can answer the question: One, the map was invented for a specific purpose: Mischief:

Messrs. Moony, Wormtail, Padfoot, and Prongs Purveyors of Aids to Magical Mischief-Makers are proud to present THE MARAUDER’S MAP.


He took out his wand, touched the parchment lightly, and said, “I solemnly swear that I am up to no good.”


“I’m getting there, Sirius, I’m getting there… well, highly exciting possibilities were open to us now that we could all transform. Soon we were leaving the Shrieking Shack and roaming the school grounds and the village by night. Sirius and James transformed into such large animals, they were able to keep a werewolf in check. I doubt whether any Hogwarts students ever found out more about the Hogwarts grounds and Hogsmeade than we did… And that’s how we came to write the Marauder’s Map, and sign it with our nicknames. Sirius is Padfoot. Peter is Wormtail. James was Prongs.”

These quotes show us that the map was intended for mischief, and specifically, was invented for James and Co. to be able to sneak around camp grounds.

The second fact that can answer this question is that the map is intelligent.

But even as he stood there, flooded with excitement, something Harry had once heard Mr. Weasley say came floating out of his memory. Never trust anything that can think for itself, if you can’t see where it keeps its brain. This map was one of those dangerous magical objects Mr. Weasley had been warning against… Aids for Magical Mischief Makers…

And by the episode of Snape we see further evidence of the map's intelligence:

“Professor Severus Snape, master of this school, commands you to yield the information you conceal!” Snape said, hitting the map with his wand. As though an invisible hand were writing upon it, words appeared on the smooth surface of the map. “Mooney presents his compliments to Professor Snape, and begs him to keep his abnormally large nose out of other people’s business.”

The third fact is that the map can change its appearance to help with the mischief:

What did he have to do? He pulled out the map again and saw to his astonishment, that a new ink figure had appeared upon it, labeled ‘Harry Potter’. This figure was standing exactly where the real Harry was standing, about halfway down the third-floor corridor. Harry watched carefully. His little Ink self appeared to be tapping the witch with his minute wand. Harry quickly took out his real wand and tapped the statue. Nothing happened. He looked back at the map. The tiniest speech bubble had appeared next to his figure. The word inside said, ‘Dissendium.’

This is incredible! The map not only deviated from its purpose (showing Hogwarts) it realized that Harry did not understand how to open the secret passage, so first it showed him the wand-tap, but Harry still didn't get it, so the second time Harry looked, it showed him the spell! So this map can realize the viewer's intention and difficulties!

So we know 4 facts from the books: 1)Not every dot appears on the map. 2)The map is intended for mischief. 3)The map is intelligent. 4)Using its intelligence, the map can change its appearance to help with the mischief.

From these four facts we can deduce that the map does not show everybody at once, but rather shows only people who the viewer is specifically looking for or that the map feels can interfere with the viewer's intended mischief (or the whatever the viewers intention is) with the map.

This is further proven by the dots shown to Harry the first time he uses it:

A labeled dot in the top left corner showed that Professor Dumbledore was pacing his study; the caretaker’s cat, Mrs. Norris, was prowling the second floor; and Peeves the Poltergeist was currently bouncing around the trophy room.

And also (GOF):

Out in the dark corridor, Harry examined the Marauder’s Map to check that the coast was still clear. Yes, the dots belonging to Filch and his cat, Mrs. Norris, were safely in their office . . . nothing else seemed to be moving apart from Peeves, though he was bouncing around the trophy room on the floor above.

In all those cases, the dots shown to Harry were those that would cause an impediment to Harry's purpose (sneaking around).

Therefore, we can answer all the questions "Why didn't x appear on the Mauraders Map" with a simple answer: It didn't affect whatever they were using the map for at the time. Thus there was no need to show them.

This explains why Lupin didn't see Peter until after he joined with Harry and Ron: because Lupin was keeping an eye out only for Harry, Peter was of no significance and thus the map didn't show him, but after he joined with Harry, it became significant for Lupin's use of the map, and thus the map showed him.

This also explains why nobody saw Moody in Crouch's trunk and Sirius or Rita Skeeter in Animagus form: Because they were insignificant for the map's purpose.

This also why Harry didn't notice impostor Moody as Crouch until he tried looking in Snape's office: Since Snape's office was significant for Harry, the map showed Crouch.

This is further proven by this statement of Fred:

“Right,” said George briskly. “Don’t forget to wipe it after you’ve used it —” “— or anyone can read it,” Fred said warningly. “Just tap it again and say, ‘Mischief managed!’ And it’ll go blank.”

Now, if there are hundreds of dots on the map, who cares if anyone can read it!? But if the map only shows what is necessary for the viewer, if an authority figure would use it, the map becomes quite dangerous indeed.

  • 5
    How can you ignore an author's answer? That makes no sense.
    – Edlothiad
    Commented Sep 14, 2017 at 13:03
  • 9
    @Edlothiad Same way I ignore her when she says Cursed Child is canon: Because not everything JKR says is canon. If her books imply one thing and she says another, I go with the books.
    – TheAsh
    Commented Sep 14, 2017 at 13:05
  • 2
    While is an astoundingly well research theory, in the end that is all it is....
    – Skooba
    Commented Sep 14, 2017 at 13:06
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    I upvoted this answer because it is well argued, but I disagree with the conclusion. I don't think the map cared much about Harry's intentions. Sneaking into forbidden places is one of the main goals of the Map, and the seven secret corridors (one of which lead to Hogsmeade) are surely very important information that the Map is supposed to relay. Hard-coding a message about how to open the secret passages seems like a completely reasonable thing to add to a good Map.
    – b_jonas
    Commented Sep 14, 2017 at 13:58
  • 4
    There's no evidence for your assertions that a) people viewing the map aren't shown on it (the included quote in fact indicates the opposite); b) Lupin should have seen Wormtail in Hagrid's hut (he says himself that he wasn't looking at the map before that evening); c) the map only shows potential trouble-makers (the later books actually describe the hundreds of dots which are moving around; Harry can't locate Malfoy among the masses); d) the Map wouldn't be of any use to anyone if found unwiped (even with hundreds of dots, it's a unique, potentially dangerous and intelligent artifact). Commented Sep 14, 2017 at 16:55

Edited to correct my faulty memory,

In the film Harry did see Peter Pettigrew. When Harry was walking down one of the corridors at night he saw Peter coming towards him on the map but he couldn't see anybody because Peter was in his Scabbers form.
Later when Lupin confiscated the map, Harry told him that it didn't work right because it showed Peter Pettigrew who was supposedly dead.

In the book Harry never uses the map when Ron has Scabbers with him. As to why Fred and George never saw him it may be explained with how the map is built.

This video of the Noble Collection Marauders Map shows separate sections of the map that allow you to essentially zoom in on a specific area. You start with a large view of all of Hogwarts and then fold out other parts of the map depending on need. As Fred and George were more intent on either getting out of Hogwarts or hiding from certain people they may not have bothered with looking for where Percy was.

As to the question of the number of people at Hogwarts which keeps popping up as a reason why they never saw him:

BeyondHogwarts lists JK Rowling saying there are around 1,000 students.

HarryPotterLexicon says the books show about 300 with 5 boys and 5 girls added to each house every year.

Another HPLexicon comment has Rowling saying 600 but admitting she is bad at math.

  • And how the map was revealed to Severus and Remus was also different in the book. In the book iirc Hermione had to go to the witch statue to get Harry's cloak back as it was too risky now that Harry had been discovered to be interested in that place - by Severus no less.
    – Pryftan
    Commented May 27, 2018 at 20:15

Hogwarts has hundreds people in it IIRC. People looking at the map would only pay attention to locations/names that were interesting for their purposes or violated expected patterns. NOBODY would be checking the location of the Gryffindor's dormitories where Scabbers was most of the time.

  • 2
    All of Britain had 3k, Hogwarts had 1000, according to JKR; and possibly fewer based on later comments and evidence from the book.
    – Kevin
    Commented Feb 21, 2012 at 3:19

I'm guessing that to see someone on the Marauder's Map the viewer has to know them rather personally (otherwise the map would be loaded with extraneous information)

All of the people who appear on the map have to be a subject of great focus in the viewer's mind (such as people securing the hallways).

Harry never looked at the map for "dad's old friends" or anything of that sort. Lupin was able to see Pettigrew because he knew Pettigrew well and had probably looked for him on the map before.

  • 10
    Nope. The map showed everyone present at Hogwarts, and didn't take into account the viewer's preferences or interests.
    – Janoma
    Commented Feb 19, 2012 at 13:46
  • 2
    In the books I've only seen reference to it being capable of revealing everyone present, not that they are all constantly shown. In the movies the map clearly only shows people relevant to the person viewing the map. Considering Hogwarts' numerous floors, rooms and passages it is infeasible that the map displays all of the thousands of dots. If the magic were to be fueled by intent then extraneous information should easily be filtered.
    – Mojo
    Commented Feb 19, 2012 at 15:49
  • And the map takes into account the person reading it as evident when Snape attempts to read the map.
    – Mojo
    Commented Feb 19, 2012 at 15:51
  • 1
    When Snape attempted to read the map, it had been turned off (with "mischief managed").
    – Martha
    Commented May 20, 2013 at 23:21
  • So why did Harry saw the name of Peter Pettigrew on the marauder map while lurking in the school? He wasn't thinking about his father friend, he was only scared of filch or rogue...
    – max pnj
    Commented Mar 1, 2016 at 18:05

There's no way that Scabbers lived with the Weasley family for 12 years and the twins never noticed him sleeping with Ron every night.

I prefer to think that the twins just assumed the map didn't work on animals. Or maybe they thought that scabbers's original name had been Peter and didn't think anything of it. It wouldn't be too strange in the wizarding world for rats to have first and last names.

Maybe they noticed and just didn't care. After all, the name didn't mean anything to them.


Isn't it obvious?

Nobody knew who Peter Pettigrew was. Just like Harry didn't know who Sirius Black was at first. They didn't teach them about Sirius Black and Peter Pettigrew. People only knew about Sirius because of his escape. So none of the students know who Pettigrew was. And Harry did see him. Remember he went and told Lupin about it?

  • 4
    So... why is this "Peter" in Ron's bed every night?
    – ike
    Commented Sep 7, 2014 at 4:41
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    Ron told Harry about the largest bit of Pettigrew found and sent back to his mum being his finger—so ye, not only did people know who Pettigrew was, they were fairly intimately familiar with the story. Commented Mar 1, 2016 at 4:20
  • 1
    Everyone thought Peter was dead. The twins would have assumed he was a homonym, or a distant relation who happened to share his common given name.
    – Pwassonne
    Commented Mar 10, 2016 at 8:42
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    As for why he was in bed with Ron, either the twins didn't look at Ron's dormitory, or they noticed and were discreet enough for once not to mention it to Ron or Harry because some things are not joking matters. Most likely they didn't look, because I would have been worried if my older brother's ex boyfriend was sleeping with my 11-12yo younger brother.
    – Pwassonne
    Commented Mar 10, 2016 at 8:44

You wouldn't be able to tell exactly where someone is. You might see Peter in the Gryffindor common room, but not that he is specifically in Ron's bed because that's just a tiny area of the castle. Also, whenever Ron was sleeping in the dorm with Scabbers up to four other people would be sleeping as well. So the dots would just be on top of each other and a mess.

To be honest, at night the Gryffindor common room would probably be just a big black blob of names and dots on the map.


Here, this is a good question, and I have a theory.

Lupin was able to see Peter Pettigrew on the Marauders' map because he was the only possessor who knew that Peter was an Animagus

Fred, George, Harry, and Snape at first did not know that Peter Pettigrew was an Animagus, but professor Lupin, his once-friend, knew it, and hence was able to see him as Peter Pettigrew on the map, and not as Scabbers.

Even if they were able to see the rat as Peter Pettigrew on the map, it wouldn't have made so much of a change to the story. And also, unlike in the book, in the movie, Harry is able to see Peter on the map, which quite of seems disastrous for this theory.

  • This is actually a great headcanon. If you would have evidence it would be great.
    – TheAsh
    Commented Jan 24, 2019 at 17:06

I think it is a combination of perception, awareness, and focus. Even if the map shows the position/direction of anyone in a given area, maybe you have to know or be looking for a certain person for their name to show up?

Honestly, if you were trying to find one particular person on the map and he was in a crowd, everyone's names would be literally on top of each other. Thus making the names unreadable. That would make no sense. So maybe you have to be focusing on that specific person or "dot" to see the name?


Lupin was one of the original creators of the Marauder's Map so he knew more about it than Harry, the twins or anyone except Peter and Sirius.

  • 1
    Yes but Fred, George and Harry were all perfectly proficient in using the Map. They never have any problems in using it or in locating people on it so it can't be that Lupin was so much better at using the Map. Unless you have some evidence to back up your point? Commented Sep 14, 2017 at 19:20

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