It was said in Prisoner of Azkaban that the Potters used Peter instead of Sirius as a Secret Keeper for the Fidelius Charm on their house because everyone would have expected them to use Sirius and so the secret would be better protected.

This made sense at the time, but Rowling has added some information about Secret Keepers in Pottermore that seems to cause a problem with this:

The Fidelius Charm is not without its weaknesses. If the Secret Keeper wishes to do so, they may divulge the information at any time (although the secret cannot be forced, bewitched or tortured out of a Secret Keeper who does not wish to give up their secret; it must be given voluntarily).
(Secret-keeper, Pottermore Book 3 Chapter 17 Moment 2)

If it cannot be forced, surely it didn't matter (protection-wise) if others knew who the Keeper was. Voldemort could have crucio-ed Sirius for months and he wouldn't get anywhere. Under these conditions, the only thing you need to consider to make someone a secret-keeper is that you trust them. Which means Sirius was a far better option than Peter.

One might think at first glance that they wanted to protect Sirius (as being tortured isn't a good thing whether or not it will reveal a secret) but since people thought he was the keeper anyway that's no protection for him.

So if Pottermore is correct, why would they pick Peter?

(I think Rowling messed up with that fact, personally. There was no reason to add it at all, as it doesn't help explain anything else I can think of)

  • 4
    Nice question :)
    – tls
    Commented Jan 16, 2015 at 9:40
  • 1
    What about legilimency? I'm not sure that would fall under any of the categories mentioned, and Voldemort was a legilimens.
    – Brian S
    Commented Jan 16, 2015 at 15:02
  • I'm thinking that Peter's cowardly and sarcastic thoughts on Sirius' plan (that Voldemort will target Sirius) "Brilliant Sirius! Voldemort goes after you - and you can't reveal the location of the Potters because you're not the secret Keeper. But what happens if Voldemort catches you and pours Veritaserum on your flea-bitten carcass and asks you. "Who is the Potter's Secret Keeper then?"
    – tls
    Commented Jan 16, 2015 at 15:36
  • 3
    Hmm. My problem with this quote from Pottermore is that the thing about torture is that it makes one want to tell the information just so the torture will stop. In that sense, the person "voluntarily" discloses the information...or tells the torturer whatever he/she wants to hear.
    – Deacon
    Commented Dec 13, 2019 at 14:04

6 Answers 6


The goal was not only to keep the secret safe, but also to send Voldemort off track.

It was not a matter of trust between Sirius or Pettigrew because up to that point the Potters trusted both of them equally.

However, Sirius knew that Voldemort would come after him thinking he is the secret keeper and even though it might not be possible to get the secret out forcefully, it would keep Voldemort away from where the secret really was.

Moreover, Sirius was probably better at escaping and hiding than Pettigrew was, and he could keep Voldemort busy trying to go after him, while the secret keeper was apparently safer, the point being to divert Voldemort's attention to somewhere unnecessary.

Moreover, Sirius and Lupin didn't trust each other and that left Peter among the Marauders.

  • 2
    No! See the quote from pottermore: "it must be given voluntarily". That means imperio is useless. And I would argue that being forced to reveal the secret unter torture is also not considered voluntarily. The quote sounds like it has absolutely no loophole. Commented Jan 16, 2015 at 15:33
  • 2
    @LarsEbert They could be tricked into giving up the secret. Or maybe there could be some sort of magical tracking device/spell that they could place on the secret keeper? I'm not sure if there is such a thing as "no loopholes" when it comes to magic, if you're strong and creative enough.
    – KSmarts
    Commented Jan 16, 2015 at 16:16
  • 8
    also, you're forgetting about coercion. He might be willing to give up the secret voluntarily if one of his loved ones or friends was being tortured. Pettigrew was mentioned to be very unpopular. I suspect there were few people that Voldemort could have hurt to coerce him to tell the secret (thinking through the standpoint of Sirius and the Potters) Commented Jan 16, 2015 at 17:04
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    @LarsEbert However, if the Secret Keeper is caught, it becomes extremely difficult to invite new friends and family to your house - the most basic example being if James and Lily had a second child who needed telling. You could have it written on a piece of parchment - like Dumbledore did for Harry in OotP - but that's a security risk (hence why Moody set fire to it once it had been read) Commented Dec 13, 2019 at 7:30
  • 1
    @WizardKnight the flaw in that argument is that just because there's nobody who likes Pettigrew doesn't mean there isn't someone that Pettigrew likes. Not many like Snape,but he'd have likely given up <any> secret to protect Lilly (given the opportunity).
    – FreeMan
    Commented Mar 17, 2021 at 16:48

The book takes precedence over Pottermore (hard canon v. soft canon). It was foolish of her to post that on secret keepers precisely for what you have pointed out. If Wormtail's trustworthiness can be taken for granted (as the Potters unfortunately did), there would be no difference between having him as a secret keeper or Sirius. Indeed, Sirius seems the better choice. I just know that the switch occurred mainly because they suspected Remus of being the spy so they switch at the last minute to confuse him. That's the best explanation given in the book.

  • While this is the correct canon reason, there is no line in the book that I am aware of which contradicts Pottermore's statement. So you're both correct ^^
    – ThreeFx
    Commented Jan 18, 2015 at 10:54

I suspect that your interpretation of the Pottermore quote is incorrect. It is not impossible to discover the secret by torturing the Secret-Keeper. What it means is that the secret can’t be forcibly extracted so long as the Secret-Keeper chooses jot to tell. But there are many ways of convincing someone to tell the secret.

Imagine if Voldemort simply asked Sirius to tell him where the Potter were hiding. Sirius would undoubtedly refuse. But not because it is not possible for him to tell, but because he doesn’t want to tell. He values the Potters more than he values Voldemort.

Now suppose that Voldemort offered him a thousand galleons. It doesn’t suddenly become impossible for Sirius to tell the secret just because Voldemort threw in a bribe. It is still impossible to force Sirius to divulge it, but he can still choose to do so if he values Voldemort + money more than the Potters.

Torture fits into this equation in the same way. It can’t force Sirius to tell anything, but it can motivate him to willingly tell. If he values being free from pain more than the Potters he will tell; if he values the Potters more he won’t tell.

In this sense there is always a point at which a Secret-Keeper can be convinced to share the secret, unless there is absolutely nothing in the world valued more than the secret. It’s only a matter of discovering what the thing of greater value is and offering it.

Therefore, it is a very dangerous situation. In Prisoner of Azkaban Fudge says that James was if the opinion that Sirius would rather die than reveal the secret. But that doesn’t mean that it would be impossible. Maybe he values something else more than life. Maybe James’s assessment was wrong.

It would therefore be expected that Voldemort would go after the Secret-Keeper. Despite everything there is no guarantee that Voldemort won’t be able to extract the secret. The only foolproof way to ensure that Voldemort can’t get the secret is to make him go after someone who does not have the ability to reveal it.

In that sense, using Peter as the Secret-Keeper has a slight advantage. It ensures that it will be truly impossible for Sirius to reveal the secret no matter what Voldemort does to him. It doesn’t put Sirius at any more risk than he would have been, because if he was actually the Secret-Keeper Voldemort would still have come after him. It doesn’t put Peter at any more risk because Voldemort wouldn’t come after him, having no reason to suspect he was the Secret-Keeper.

Though Sirius would presumably be be better than Peter at not succumbing to torture, this wasn’t considered a major issue because they didn’t expect Voldemort to torture Peter; his efforts would be focused on Sirius whom he believed to be the Secret-Keeper.

  • 2
    "Torture […] can’t force Sirius to tell anything, but it can motivate him to willingly tell." Isn't that the only way that torture ever works, when it comes to revealing secrets? If it can still work that way, what did the Pottermore quote mean by "cannot be tortured out"?
    – George T
    Commented Dec 14, 2019 at 14:17
  • the only way that torture can work is if it persuades him to willingly tell...
    – ava
    Commented Mar 17, 2021 at 16:28
  • Actually this makes no sense. If Voldemort actually catches Sirius and can possibly torture him to the point of making him divulge the secret if he knew it, then at that point Sirius would divulge the real secret-keeper, so it does nothing. In fact, it's worse because Voldemort can use Veritasium to find out who is the real secret-keeper (no need even for torture).
    – user21820
    Commented Oct 6, 2021 at 9:54

Maybe it was just bad judgement/mistake by them? It's neither impossible nor too improbable for someone to trust one of his best friends. Considering the specifics of the Fidelius spell, the Secret Keeper is the weakest point is the protection. So choosing a cowardly and quite incompetent Peter was really a bad decision even if he wasn't a traitor.

Going out of the lore - this decision it is one of the cornerstones of the main plot and it can't be considered just pulled out of thin air. There are many things in the books that people just decide to do. Same goes for real life.


The Potter's decided to use Sirius as a decoy. Remember, they thought that Lupin was the spy, based on when Lupin says,

"Unless you thought I was the spy?"

"I confess that I did."

So they wouldn't have used Lupin. Then, in the Shrieking Shack, after Peter is discovered, Sirius says:

"So we switched. I thought for sure he would come after me. I never thought he would use a weak, talentless thing like you."

So this proves that they switched because they thought Voldemort would certainly come after and torture Sirius, and essentially not at all trying to use Peter, to throw Voldemort and Lupin, who they thought was the spy, off the scent.


This has always been a theory of mine. And it’s probably not true but it’s my head canon so take it as you will.

I like to think Dumbledore told James and Lily about the prophecy and they chose for it to be them over the Longbottoms. Maybe the Longbottoms were even there, because they are hospitalized, it’s possible they all knew and we don’t know that. I think James and Lily talked about it and they said Voldemort thinks it’s us so let’s prepare this love charm that will fuck his day up. Everything else that powerful in the Harry Potter universe takes time to do so it would make sense that a charm that powerful and old would take time. I definitely don’t buy that it was just a thing that happened.

I think they knew Harry would have a hard life but they felt they couldn’t ask anyone else to do this. I also like to think they thought about where Harry would go and had planned on him being with Sirius. They never even gave him a godmother but Sirius going to jail fucked that up. So Dumbledore just did the best he could. I like to think that when James gave Albus the invisibility cloak he told him of their plan and asked them to take care of Harry and said goodbye, which is why Hagrid was able to get there and take Harry before any muggle police came. I mean the house exploded, the police would have been called right away, so Hagrid had to get there really quick. Also, James and Lily were both head boy and girl so they may have had a closer relationship with Dumbledore than we know.

So in my mind they chose Peter because they knew he’d betray them and lead Voldemort to them. But that’s just my musings and what I’d like to believe.

  • "head canon" answers tend to not be taken well here. People tend to prefer something based on original and/or "official" canon material. If you've got things from the books, JKR (or her other writings) that will support your head canon, please edit them in and you'll likely get a better response.
    – FreeMan
    Commented Oct 4, 2021 at 16:33

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