Chapter 18 of Harry Potter and the Prisoner of Azkaban: Moony, Wormtail, Padfoot, and Prongs← Chapter 17 | Chapter 19 →


Spoiler warning: Plot and/or ending details follow.

Harry, Ron, and Hermione insist Lupin and Black must be crazy. Scabbers could not be Peter Pettigrew, Sirius Black murdered him twelve years ago. Black says he did try to kill Pettigrew, but, unknown to him, Peter escaped. Black lunges at Scabbers. Ron, still clutching Scabbers, yells in pain when his injured leg is jostled. Lupin restrains his old friend, insisting that Harry must understand everything before Pettigrew dies. Black acquiesces, but demands Lupin be quick, he wants to commit the murder for which he was imprisoned. When Ron reminds Black there were witnesses who saw him kill Pettigrew and the Muggles, Black contends they were fooled. Lupin says that everyone, including himself, thought Sirius killed Pettigrew. He only realized Sirius was innocent when he saw Pettigrew's name on the Marauder's Map. Hermione points out that Pettigrew is not listed among the seven registered Animagi. Lupin claims there were three unregistered Animagi running around Hogwarts.

Ron, noting a door apparently opening by itself, says he believes the Shrieking Shack is haunted, but Lupin claims it is not. The howls the villagers heard were his, not Ghosts. Before there was a potion to allow a Werewolf to retain his mind, the Shrieking Shack was built specifically to confine Lupin during his transformations. The Whomping Willow was planted to guard the tunnel leading to the shack. Terrible as the transformations were, Lupin did have three great friends: Sirius Black, Peter Pettigrew, and James Potter. After discovering he was a Werewolf, rather than shunning their friend, they secretly became Animagi to support him. It took them three years to learn how, perfecting it in their fifth year. James and Black learned on their own, but Pettigrew needed their help. When transformed, they could safely run with Lupin in the Forbidden Forest. Sirius and James were large enough to keep a Werewolf in check, though there were near misses. Their Animagus forms determined their nicknames; Black was Padfoot, James was Prongs. Pettigrew, the rat, was Wormtail.

Harry asks what animal his father was, but Hermione interrupts, saying it was dangerous to allow a Werewolf to run free. Lupin admits it was, but they were young and uncaring. Lupin regrets never telling Dumbledore that Black is an Animagus, but says he was ashamed to admit that he betrayed Dumbledore's trust by roaming the village as a Werewolf. Lupin says that he believed Black was serving Voldemort and convinced himself that Black used Dark Magic to enter the castle, rather than his Animagus form. He confesses that Snape was partially right, that by remaining silent, he was aiding Black. Black demands to know how Snape is involved, and Lupin explains that Snape is now a Hogwarts teacher. He tells the Trio that Black once tricked Snape, who had become curious about Lupin's monthly disappearances. Black told him about the Whomping Willow and how to get into the tunnel. It was James' last-minute intervention that saved Snape from meeting the deadly Werewolf that Lupin had transformed into. Dumbledore had, of course, forbidden Snape from revealing anything about Lupin's condition.

Says Harry, "So that's why Snape hates you." Behind Lupin, pulling off the Invisibility Cloak, Snape replies, "That's right."



Many questions are answered, but Harry is barely able to digest what is happening. Nothing is what it seemed, and Harry had become so entrenched in his belief that Sirius Black was guilty that he is barely able to consider any other explanation. The revelations concerning Lupin's and Pettigrew's roles only add further confusion. Regardless, Harry learns much about his father and his comrades that he never knew before, and gains some insight into Snape's animosity towards him and James Potter.

There have been few Animagi; presumably, mastering the ability is too difficult a feat for most Wizards, and it is mentioned here that Pettigrew succeeded only because James Potter and Sirius Black coached him. Of the four Marauders, Pettigrew was the weakest - physically, intellectually, and magically lagging behind the others in ability. Being an Animagus is certainly a useful ability, though it is a skill that can also be used for unethical and illegal purposes. That is why all Animagus Wizards must be registered with the Ministry of Magic, failing to do so is a serious crime. That obviously never deterred James Potter, Sirius Black, and Peter Pettigrew, whose solidarity for their friend, Remus Lupin, outweighed any legal concerns.

A minor note on timing may be of interest here. It is at the beginning of this book, Harry's third year, that we, and Harry, are introduced to the Animagus transform. Lupin says here that James and Sirius had mastered the technique after three years, performing it in their fifth year; this would indicate that they had started their research immediately upon learning of the transformation and had then taken somewhat less than three years to manage it themselves. It is possible that James and Sirius knew of the transformation before it was taught to them, but it is a very rare skill, we are told. This also means that James and Sirius had learned of Lupin's werewolf nature sometime within their first two years at Hogwarts.

The door opening, apparently by itself, prompting Ron to comment that the Shrieking Shack is haunted, should be noted. It is reasonably clear that this is when Snape, under Harry's Invisibility Cloak, entered the room, though it is entirely possible that he had been listening from outside. Thus, he will certainly have heard that the Marauders were Animagi, but may have missed that Scabbers is Pettigrew, or, being Snape, he may simply refuse to believe it. In one of the bits of misdirection that the author is good at, our curiosity about the door is promptly overshadowed by Lupin's ongoing revelations. One wonders why Lupin and Sirius don't seem concerned about the door; but we should note that neither of them yet knows about Harry's Invisibility Cloak, and as such things are quite rare, in their minds it is probably much more likely that the door moving was due to the Shack settling than by someone (Snape) spying on them invisibly.

We know that Dumbledore knows of Snape's rescue by James from the changed Lupin, and thus that Snape was aware of Lupin's nature when he was a student. It is possible that he could also have learned of James, Sirius, and Pettigrew sneaking off to have adventures with a potentially deadly werewolf. This could be a mistake on the authors part, but, if in fact Dumbledore did know about the illegal Animagi, then one should then assume that Lupin has lulled himself into believing that Dumbledore never found out. It is also possible that the events with Snape and Lupin occurred before Sirius, James, and Pettigrew had mastered the Animagus transform; the possibility of wandering with the werewolf (to use Gilderoy Lockhart's florid speech patterns) could well have not occurred to them yet.



Study questions are meant to be left for each student to answer; please don't answer them here.


  1. Why did Sirius Black, James Potter, and Peter Pettigrew become unregistered Animagi? How did they achieve this?
  2. What do Lupin and Black reveal about "Scabbers"?
  3. Why does Black want to kill Pettigrew?
  4. Why was the Shrieking Shack built? Is it haunted?
  5. What is Severus Snape's past connection to Black, Lupin, Pettigrew, and James Potter?
  6. Do Black and Lupin kill Pettigrew? Did Harry do anything?

Further Study

  1. What might James Potter's nickname (Prongs) indicate about his Animagus animal shape?
  2. Why have there been so few Animagi in Wizarding history?
  3. Why do all Wizard Animagi have to be registered with the Ministry of Magic?
  4. Although Lupin had always believed Black was guilty, why did he never reveal Black's secret Animagus ability?

Greater Picture

Intermediate warning: Details follow which you may not wish to read at your current level.

An Animagus is unable to choose his animal shape; rather, it reflects that person's inner character. The rat form certainly will seem appropriate for Pettigrew (Wormtail), representing that animal's less desirable traits, while Sirius' (Padfoot) dog shape emphasizes amity, courage, and fidelity. It should be noted that in the Western world, the rat is generally associated with unsavory characteristics such as cowardice, treachery, deceit, and filth. However, in other cultures it can represent admirable qualities, and in the Chinese zodiac the Rat symbolizes intelligence, adaptability, and industriousness. Rowling is using the Western characterization here, though some Eastern characteristics could also apply to Pettigrew including edginess, shrewdness, and opportunism, traits often associated with Slytherin. Why the Sorting Hat placed Pettigrew into Gryffindor is a mysterious decision and is never explained; Slytherin would seem more appropriate. However, that Pettigrew was able to become an Animagus at all may indicate that he has some noteworthy magical ability, though bravery, loyalty, and nobility, Gryffindor traits, hardly seem to be among his attributes.

"Prongs" refers to James Potter's Animagus form, a stag. Interestingly, it is the same shape as Harry's fully-formed Patronus. This is why Lupin was so shaken after the Quidditch match with Ravenclaw in a previous chapter, recognizing it as James' Animagus shape. With the possible exception of Black, who had been present at an earlier match and might have managed to see this one, and perhaps the supposedly missing Scabbers (Pettigrew), nobody else present could have understood the shape's significance. Harry, busy catching the Snitch, is unable to see it himself, thus missing the vital clue as to what James' nickname might refer to. In this chapter, we see that Harry asks what his father's Animagus' shape was, but Hermione inconveniently interrupts before we are given an answer. This is another example of the use of timing and misdirection which the author excels at; while the question is not answered, somehow the fact that it has been asked seems sufficient, given the flow of events.

Much of Ron's reluctance to accept that Scabbers may actually be Pettigrew is likely denial on his part. If Scabbers is Pettigrew, then Ron has been sharing his bed, unknowingly, with a grown man for the past three years at least. This prospect, horrifying for Ron to contemplate, is something he is eventually unable to deny.

Harry is also reluctant to accept what is being revealed, which perhaps stems from the commonly shared belief that Sirius betrayed his parents. He is, however, being convinced by Lupin and Black's precise recounting of events, aided by his personal trust in Lupin. Snape's appearance will actually bolster Black's account as Snape rejects everything Lupin and Black claim, even those events that are immediately provable. Harry's distrust of Snape, combined with Snape's attempted refutation, will do more than anything to convince Harry that Black's intentions are good.

It is mentioned that Pettigrew's inclusion in the Marauders seems odd. The other three befriended Pettigrew because he ingratiated himself into their circle, and presumably because he was able to think up interesting mischief for them to do. We will see later that the Marauders, with the possible exception of Lupin, were more than mischievous, and that aspect of Pettigrew's personality may have appealed to them. Pettigrew's weak, cowardly character eventually resulted in his defecting to Voldemort and betraying his friends.

As mentioned, based on what has been revealed since he entered the room under the Invisibility Cloak, Snape will have heard that the Marauders are Animagi, but not Black's and Lupin's claim that Pettigrew is alive as Scabbers. However, this hardly seems germane to Snape, and, in the next chapter, Snape forms his own theory about what happened, acting on those ideas, and literally stifling any dissent.

In the analysis section above, it is mentioned that as Dumbledore knew of Snape being aware, as a student, that Lupin was a werewolf, it is possible that he also knew of the other antics of the Marauders. We cannot judge at this point, but Dumbledore does seem to suggest in a later chapter that he had not known of the three Marauders being Animagi until told by Sirius. While Dumbledore is aware of almost everything happening in the school, it seems that he is unaware of Sirius' ability to change into a dog, as nothing is done to prevent Sirius entering the school in his canine shape. The teachers and prefects are told to watch out for Sirius, there is never any mention that he might appear as a dog. We must conclude that Dumbledore was unaware of many of the Marauders' extracurricular activities.

So why does Lupin say that Snape had been told not to reveal his secret? Dumbledore, in September when Lupin was introduced to the school, still accepted the Ministry belief that Sirius was the secret-keeper who revealed the Potter's whereabouts to Voldemort. Dumbledore already knew of Snape's hatred of James Potter for having saved his life, and could assume, knowing of Snape's feelings for Lily Evans, that Sirius would also be greatly hated. Dumbledore further knew, because Snape freely expressed it, that Snape felt that the allegiance between Lupin and Sirius was still strong despite Sirius' betrayal of the Potters. (We overheard Snape reiterating this belief after Sirius' first attempt to get into the Gryffindor common room, when Harry and all the rest of the students were sleeping in the Great Hall.) Of course there is also the jealousy – if his mere existence wasn't enough, Lupin had the effrontery to be accepted into the job that Snape wanted. And finally, Snape was compelled to brew, every month, the doses of Wolfsbane Potion that kept Lupin from being a danger. Even if Dumbledore had to warn other staff members about revealing Lupin's secret, we can be certain that he knew enough about the relationship between Lupin and Snape to feel that reinforcement of the directive would be required.