Did Peter Pettigrew need the wand to transform back into a rat? [duplicate]

Question

Inspired by this question.

In Harry Potter and the Prisoner of Azkaban, Peter Pettigrew is captured and is in the process of being brought to Hogwarts when he escapes.

In order to escape, Peter uses his ability as an Animagus to transform into a rat.

The scene is described in the book as:

Pettigrew had dived for Lupin's dropped wand. Ron, unsteady on his bandaged leg, fell. There was a bang, a burst of light - and Ron lay motionless on the ground. Another bang - Crookshanks flew into the air and back to the earth in a heap.

'Expelliarmus!' Harry yelled, pointing his own wand at Pettigrew; Lupin's wand flew high into the air and out of sight.

'Stay where you are!' Harry shouted, running forwards.

Too late. Pettigrew had transformed.

Harry saw his bald tail whip through the manacle on Ron's outstretched arm and heard a scurrying through the grass.

-Harry Potter and the Prisoner of Azkaban

The scene as depicted in the movie shows Peter touch Lupin's wand to his head before transforming into a rat. YouTube clip.

In this specific scenario, did Peter need the wand in order to transform back into a rat?

Answer 1

Actually I believe Animagi do not need wands to transform themselves. As suggested by Sirius Black in Harry Potter and the Prisoner of Azkaban, Chapter 19: The Servant of Lord Voldemort

"Er -- Mr. Black -- Sirius?" said Hermione.

Black jumped at being addressed like this and stared at Hermione as though he had never seen anything quite like her.

"If you don't mind me asking, how -- how did you get out of Azkaban, if you didn't use Dark Magic?"

...

"I don't know how I did it," he said slowly. "I think the only reason I never lost my mind is that I knew I was innocent. That wasn't a happy thought, so the dementors couldn't suck it out of me... but it kept me sane and knowing who I am... helped me keep my powers... so when it all became ... too much... I could transform in my cell... become a dog. Dementors can't see, you know...." He swallowed. "They feel their way toward people by feeding off their emotions.... They could tell that my feelings were less -- less human, less complex when I was a dog... but they thought, of course, that I was losing my mind like everyone else in there, so it didn't trouble them. But I was weak, very weak, and I had no hope of driving them away from me without a wand...."

So Sirius could transform into his Animagus form without using a wand. I believe Pettigrew grabbed the wand just to attack Harry and the others, i.e., to buy himself as much time as he could. As soon as he was disarmed, he had no option but to transform into a rat and flee.

Also, I'd like to point out that the movies do deviate from the books in several aspects. So looking for canonical facts in the books based on certain movie scenes will just add to the confusion.

Answer 2

Depends on his skill level.

To return to a human form, visualise your human self as clearly as you can. This should be sufficient, but do not panic if the transformation does not occur immediately. With practice, you will be able to slip in and out of your animal form at will, simply by visualising the creature. Advanced Animagi can transform without wands.
_{Pottermore - Animagi (behind paywall)}

Answer 3

Well, I think we can be quite confident that in general you don't need a wand to turn into an animal as an Animagus - that's sort of what's so special, and why

'[...] the Ministry keeps tabs on witches and wizards who can become animals; there's a register showing what animal they become, and their markings and things [...] and there have only been seven Animagi this century [...]'

Harry Potter and the Prisoner of Azkaban - p.257 - Bloomsbury - Chapter 18, Moony, Wormtail, Padfoot and Prongs

Indeed, Animagi are explictly described earlier in The Prisoner of Azkaban as

[...] wizards who could transform at will into animals [...]

Harry Potter and the Prisoner of Azkaban - pp.83-4 - Bloomsbury - Chapter 6, Talons and Tea Leaves

What's more, transforming humans into animals isn't, apparently, such a big thing. We see imposter Moody turn Draco Malfoy into a ferret, we see Fred and George's canary creams turn Neville into a canary, we see Hagrid having enough confidence to attempt to turn Dudley into a pig. He fails, but still. We even see people transforming themselves, as when we see Viktor Krum (albeit ineptly) attempt to transform himself into a shark and get most of the way. Hard to see what all the fuss is about the Animagus transformation if these circumstances, unless you can do it at will.

But rather than reasoning about what's probable, we can simply refer to Sirius himself telling us how he could transform into a dog in his cell in Azkaban (also referred to in ʀᴇᴅ_ᴅᴇᴠɪʟ226's answer)

'[...] so when it all became ... too much ... I could transform in my cell ... become a dog.'

Harry Potter and the Prisoner of Azkaban - p.272 - Bloomsbury - Chapter 19, The Servant of Lord Voldemort

But of course, you asked about "this specific scenario" and I have two responses to that. The first is that it's very hard to see why not. Again, the power of the Animagus transformation seems to be that you can transform at will, otherwise the Ministry seems to have about as much need to keep tabs on Animagi as it does to keep tabs on every graduand of Hogwarts, and half of those who flunked.

But more concretely, Sirius explicitly warns Peter:

'But if you transform, Peter,' growled Black, his own wand pointing at Pettigrew, too, 'we will kill you. You agree, Harry?'

Harry Potter and the Prisoner of Azkaban - p.276 - Bloomsbury - Chapter 19, The Servant of Lord Voldemort

Kind of a pointless threat otherwise, really, isn't it? And let's remember, there's nothing that's happened to Peter that we have any reason to imagine would stop him transforming, except that he was forced to transform by the man who's just warned him not to transform again.

Answer 4

Based solely on Book and Movie evidence it is ambiguous.

However, I believe the answer is Yes, he did for the following reasons.

1. He was forcefully transformed into a human against his will. This is a unique situation in the books and therefore doesn't follow the typical observed rules of Animagus transformation.
2. Sirius thought that chaining him up would help prevent him from escaping. Chains seem quite useless (and in fact more of a burden) if the subject is able to transform at will into a rat.

   "And two of us should be chained to this," said Black, nudging Pettigrew with his toe. "Just to make sure." - Harry Potter and the Prisoner of Azkaban

3. Lupin was the one covering Peter with his wand. So if Lupin was preventing Peter from transforming; Peter could have transformed as soon as Lupin was out of the picture.

   Getting back into the tunnel was difficult. Lupin, Pettigrew, and Ron had to turn sideways to manage it; Lupin still had Pettigrew covered with his wand. - Harry Potter and the Prisoner of Azkaban

4. Crookshanks was watching the werewolf and Ron was injured; therefore neither were really a threat.

   There was a terrible snarling noise. Lupin's head was lengthening. So was his body. His shoulders were hunching. Hair was sprouting visibly on his face and hands, which were curling into clawed paws. Crookshanks's hair was on end again; he was backing away

   ...

   Pettigrew had dived for Lupin's dropped wand. Ron, unsteady on his bandaged leg, fell.

   - Harry Potter and the Prisoner of Azkaban

5. Despite all of this, Peter still thought it necessary to reach for the wand.

For these reasons, I believe Peter did need the wand in order to transform back into a rat.