This is the third of a three-part question on the basilisk plot in Harry Potter and the Chamber of Secrets that I'm looking for CANON COMPLIANT explanations for. By "canon compliant", I mean within the spirit of canon, answers directly from the book(s), or quotes from J.K. Rowling.¹

  • How did Tom Riddle come to know about the Chamber and Slytherin's legend and the basilisk? How did he know where it was located when over at least 800 years no one else had been able to find it?
  • How did Tom Riddle interact with the basilisk without being killed by the basilisk's gaze? Was it because he had created at least one Horcrux (the diary; the ring) by the time he made contact with the basilisk?
  • As mentioned in question two, Professor Binns says, "Slytherin, according to the legend, sealed the Chamber of Secrets so that none would be able to open it until his own true heir arrived at the school. The heir alone would be able to unseal the Chamber of Secrets, unleash the horror within [...]" (CoS - pages 150-151 - US Hardcover) Why did it take 800+ years for Slytherin's "true heir" to be born? It would seem logical that there would have been numerous descendants of Slytherin's over the course of almost 1000 years. Why Tom Riddle as the "true heir"?

¹ I find the Harry Potter Wiki to be inconsistent and oftentimes incorrect. I am not looking for any answer(s) from the HP Wiki. Just an FYI.

Question One - How Did Hogwarts Feasibly Accommodate a Basilisk 800-1000+ Years Ago

Question Two - How Was the Legend of the Basilisk Established?

  • I'm more wondering how no one else found out where it is located. Are Parseltongues really that rare? Even if they aren't, people like Dumbledore can apparently teach themselves Parseltongue, and Ron opens the Chamber without even understanding what he himself is saying. Not to mention, the Chamber is freaking huge, how did no one figure out there was a big freaking room no one explored before?
    – trysis
    Commented May 26, 2014 at 1:32
  • @trysis the impression i got from watching the movie is that the chamber was actually far below Hogwarts, and possibly far enough to the side that it could actually be under the lake. While not canonical, this could suggest a reasonable explanation why it was never found before.
    – user11521
    Commented Jul 17, 2014 at 19:19
  • 1
    @trysis - Yes, Parselmouths are super rare -- like the rarest of the rare. Parseltongue, according to JKR, is exclusively passed down the Slytherin line; it is not a teachable language because not enough Parselmouths exist who could logically teach it. Ron imitated Parseltongue to gain access to the chamber, but he didn't know what he was saying. So, yeah, Parseltongue is an extraordinarily rare gift. :) Commented Jul 18, 2014 at 21:23
  • 1
    @Slytherincess, so how in the hell did Dumbledore learn? I know he's a genius/amazing, but if the Slytherin line is pretty much the only line that knows Parseltongue, and Voldemort's family is supposed to be the last descendants of Slytherin, that means Dumbledore had to learn from them, and they were kind of recluses, except Voldemort, but... well...
    – trysis
    Commented Jul 18, 2014 at 23:23
  • @Michael - Actually, Pottermore indicates that the chamber was indeed quite far underground; J.K. Rowling discusses it when she talks about how the plumbing system evolved in Hogwarts over the years. I don't have a direct link handy, but at Pottermore the information would be, obviously, in the book two section, under the plumbing extra. :) Commented Jul 19, 2014 at 5:59

11 Answers 11


I will admit, I don't have canon evidence. It may exist, but if it does, I have not seen any. Heck, the fact you are asking this is good evidence that there is not. :)

But, within reason, maybe Tom found the Basilisk because he was a Parselmouth. It is an exceptionally rare gift, so it's possible that he was the first Parselmouth that had been at Hogwarts since Slytherin. Hogwarts is large, and we don't know for certain where the basilisk was all those years. Tom was renowned for knowing Hogwarts better than anyone, or at least so it was assumed (see his hiding of Ravenclaw's Diadem).

My theory that I've always held to is that Tom simply stumbled upon the basilisk and communicated with it through the pipes, similarly to how Harry heard it. It's likely that he found out about the CoS through the basilisk itself.

  • 15
    But didn't the basilisk only roam the pipes after it had been awoken by Slytherin's heir? It seems that Tom wouldn't be able to talk to the basilisk until he summoned it.
    – Dason
    Commented Mar 13, 2012 at 2:52
  • 2
    It's entirely possible he tried based off of what he knew from the legend. We don't know what is required to summon it; it could be as simple as speaking to it in Parselmouth from within the Castle. Commented Mar 13, 2012 at 3:21
  • 17
    It's possible he was the only Parslemouth in 800 years to visit the forbidden location of... THE GIRLS' LAVATORY!
    – Zibbobz
    Commented Aug 13, 2014 at 14:54
  • How does awakening work in this context? Would the basilisk have sensed Tom's presence somehow, or had it been moving around the school all this time, and Tom was the only one able to hear it and communicate with it? Commented Mar 27, 2016 at 16:42
  • 'so it's possible that he was the first Parselmouth that had been at Hogwarts since Slytherin.' The Gaunt family bragged about it, for instance, and there is evidence that it had been opened more than once since Slytherin left and Riddle entered. Rowling talks about this: pottermore.com/writing-by-jk-rowling/chamber-of-secrets
    – Pryftan
    Commented Dec 21, 2017 at 23:02

How did Tom Riddle come to know about the Chamber and Slytherin's legend and the basilisk?

Your other question quote Prof. Binns. It WAS a known legend. Naturally, Tom would have known - he was VERY plugged in.

How did he know where it was located when over at least 800 years no one else had been able to find it?

No canon evidence - but remember that Dumbledore was able to detect traces of Voldemort's magic when hunting for the Horcrux with Harry in HBP in the cave. Similarly, Riddle could have detected the traces of Slytherin's magic - he was probably extra attuned to it due to being both the descendant of Slythrin AND a major league Dark wizard.

How did Tom Riddle interact with the basilisk without being killed by the basilisk's gaze?

Same way Ginny did. Or Harry (if you call that "interaction" :)

He didn't look at basilisk. He merely closed his eyes or looked away, and spoke and listened. Or for that matter - being a powerful wizard - he could have made some magical barrier blocking the serpent's gaze.

Remember that the gaze works line-of-sight (2-way at that) only! It's not enough for Basilisk to look at you (otherwise, he'd have killed Harry the moment of appearance into the Chamber, way before Fawkes showed up) - YOU have to look at his eyes as well.

Why did it take 800+ years for Slytherin's "true heir" to be born?

No canon evidence, but given the inbred state of Gaunts, perhaps it took a mortal's bloodline to invogorate Slytherin genetics to produce a wizard of such power? :)

  • 1
    @Slytherincess Have to agree with DVK that whether or not someone can answer your question about the origin of the legend, it was indeed known to be known. Tom, knowing his own lineage, would have sought it out relentlessly. This links to your other question about the true heir. Maybe Tom was the only one who had motive to seek it out? Maybe it's not so hard to find if you look? Heck, Harry, Hermione, and Ron found it. Good points, DVK!
    – Sheph
    Commented Mar 13, 2012 at 15:16
  • @Sheph1 The Troublesome Three only found it due to Moaning Myrtle, the spilled water, and Harry hearing the Basilisk..These all happened only because Tom had found the Chamber previously. Commented Mar 13, 2012 at 16:28
  • 2
    Very true! But help will always be given at Hogwarts to those who ask!
    – Sheph
    Commented Mar 13, 2012 at 17:07
  • 1
    In regard to the gaze. All he had to do was tell the Basilisk to close ITS eyes in Parselmouth. As Heir of Slytherin, he supposedly (and does) can "control" the beast after-all. Commented Jan 13, 2013 at 23:35
  • Tom "Voldemort" Riddle was the Heir of Slytherin, himself. If anyone could get near the Basilisk, without fear of death, it's him.
    – user35971
    Commented Nov 19, 2014 at 13:31

I’m using parts of the Pottermore update about the Chamber of Secrets to answer your question (transcript), and making educated guesses about the others.

  • How did Tom Riddle come to know about the Chamber and Slytherin’s legend and the basilisk?

    Salazar Slytherin told certain people about the Chamber before he left the school; that started the legend off. Then there were generations of Gaunts who attended the school, who discovered/knew about the Chamber and perpetuated the legend:

    Whispers that a monster lived in the depths of the castle were also prevalent for centuries. Again, this is because those who could hear and speak to it were not always as discreet as they might have been: the Gaunt family could not resist boasting of their knowledge.

    We don’t know exactly how the rumour was passed on – word of mouth, probably – but Riddle could have learnt of it this way. He was fascinated by Hogwarts, and I’m sure he read Hogwarts: A History.

    That’s how he knew about the legend of the Chamber. As for the Basilisk within, I imagine he heard it moving within the pipes, and was able to talk to it.

  • How did he know where it was located when over at least 800 years no one else had been able to find it?

    The Gaunts definitely knew about the Chamber, and some of them even deigned to enter it:

    There is clear evidence that the Chamber was opened more than once between the death of Slytherin and the entrance of Tom Riddle in the twentieth century.

    So the location of the Chamber was not “lost” for 800+ years.

    That said, Riddle never knew his ancestors, so he didn’t learn the location from them. I suspect Parseltongue had a hand in this, and the Basilisk was probably keen to help.

  • How did Tom Riddle interact with the basilisk without being killed by the basilisk’s gaze?

    It wasn’t a Horcrux. According to the timeline you wrote in answer to What order were the Hercules made in?, his first Horcrux wouldn’t be created until after he opened the Chamber and killed Moaning Myrtle.

    I imagine he used Parseltongue to communicate with the Basilisk remotely, or told it to close its eyes in his presence. There must be some way to do it: Slytherin wouldn’t design a monster that his descendants couldn’t control.

  • Why did it take 800+ years for Slytherin’s “true heir” to be born?

    One thing we learn from Pottermore is that none of the Gaunts released the monster:

    As nobody else could hear the creature sliding beneath floorboards or, latterly, through the plumbing, they did not have many believers, and none, until Riddle, dared unleash the monster on the castle.

    In the absence of actual attacks to support the legend, you can see how the idea of a “true heir” would spring up. So it could just be hearsay that arose in 800+ years of waiting.

    Alternatively, it could be that “true heir” doesn’t refer to bloodlines, but intention. Only Riddle carried through with Slytherin’s threat to purge the school of Muggle-borns, so in that sense he’s closer to Slytherin than any of the Gaunts.

    As for why the Gaunts never released it, I would guess that coming from a family of people who spent generations talking about the Chamber might make you prime suspect if it were ever opened. They’re stupid, but not that stupid.

  • 1
    This ought to be the accepted answer. It is the only one that offers canon evidence and points out the misconception in the question itself (though of course it wasn't known for sure at the time the question was asked that it was a misconception). Commented May 4, 2016 at 13:30

I made a joke about it, but it may be that he actually was the only parsletongue ever to visit the Girls' Lavatory (with wicked intention at least...presumably at least a few girls in Hogwarts History spoke parsletongue too).

He had reason to be there after all.

Since he was responsible for Moaning Myrtle's death in the creation of his second Horcrux.

And if he so happened to have a pet snake that he spoke to while there...well, that'd just be even more convenient then, wouldn't it?

  • 2
    He killed Myrtle with the basilisk though--he couldn't have been in there with it until after having opened the chamber already.
    – Milo P
    Commented Oct 10, 2014 at 6:40
  • I am 99.99% certain that the Horcruxes were destroyed in the order of their creation (Which may have made the afterlife for Riddle even more painful than otherwise.)
    – EvilSnack
    Commented Oct 1, 2016 at 22:00

As for why it took 800 years or more for the heir to show up... Slytherin likely didn't send his children to Hogwarts, given his distrust of the other founders. It's heavily implied that Marvolo Gaunt didn't send his children to Hogwarts either. It's stated that attendance wasn't compulsory and that parents had the right to homeschool their children. Given that, and the fact that we have parents at the beginning and end of Slytherin's line that probably didn't send their children to Hogwarts, it's possible that no heir of Slytherin ever WENT to Hogwarts until Tom, who didn't have the option of being taught by his parents.

But also... Who says Tom is the first of Slytherin's heirs to find the basilisk? The chamber had been opened 50 years before the events of CoS, but most people didn't know it because there was a huge coverup about it. For all we know there could have been more periods of attacks on muggle borns. Maybe previous heirs got cold feet; maybe they framed someone else just like Tom did, when it was no longer in their best interest to continue the attacks. The legend stayed alive somehow. Maybe "Hogwarts, a History" mentions mysterious deaths in past centuries, muggle-borns being killed by mysterious means and the culprits never being found. Maybe they were assumed to be hate crimes.

So there are a lot of explanations as to the last part of your question.


The comment on Slytherin's true heir could be interpreted in three ways that the chamber is sealed until [Slytherin's] own true heir arrived at the school.

One interpretation which indicates that the comment is true is that depending on what it means by sealed it could mean that the chamber was sealed up in a way that not even a Parseltongue could open it. Slytherin's true heir probably came and went long before Tom, unsealing it but didn't seal it up properly so then any Parseltongue could open the chamber. thus Tom isn't a true heir and just had his ego stroked think that we was the true heir because he could open it.

The second interpretation is that the comment is false as Harry was able to open the chamber only because he had stolen the true heir's power and Ginny was able to open it because she was being manipulated. I'd doubt that you could call either a "true heir of Slytherin".

The third interpretation is that which contradicts the second is Ginny could be mistaken given that later we learn that Tom's book was a horcrux with a part of his soul so that would mean that the method to identify the true heir is by the soul, using Soul Birth (out of universe I know, but I could be logical) this would mean that Slytherin's True Heir could be thousands of years away as Soul Heirs may not be related at all by Blood. this also could mean that Harry became a walking horcrux himself when his parents died.

NOTE: I haven't watched Deathly Hallows Part 2 or read the book, the last sentence is an assumption (though I'd be s****** myself if I just hit the nail dead on).


Maybe the Chamber just shows itself only to the true heir of Slytherin.Maybe it was never found by other wizards just because it did not want to be found until the person who's going to fulfill Slytherin's intentions shows up.That person was clearly Riddle. Just a guess.

  • Hello Karen, and welcome to StackExchange. As it is, this answer is very theoretical, starting with “maybe” a lot and ending with “just a guess”. On StackExchange, we expect answers to be, to the greatest extent possible, verifiable, objective, and authoritative; this means backing up one’s claims with citations from canon material wherever possible. In this case, there is actually canon material available that proves your answer to be incorrect, in that the Chamber had been opened before Riddle did so (see Alex’ answer above). Commented Mar 27, 2016 at 21:04

Here is what I would be thinking if I was Tom Riddle assuming I had learned the legend in an early year probably second year.

  1. I can talk to snakes therefore I am a Parselmouth.

  2. There is no one else like me here.

  3. My father is not in the wizard records therefore my mother must be a wizard.

  4. Who are any existing female Parselmouths?

  5. Upon learning that he could be wondering what is the connection to Slytherin if any?

  6. establishing this knowledge he would likely acknowledge "I must be the Heir of Slytherin."

  7. If I was so obsessed I would then reason "Slytherin must have made the chamber accessible only to someone who could speak Parseltongue."

  8. "I theorize that the entrance would have the appearance of a snake since I will have to speak to it to make it open."

  9. Then it would be a bizarre matter of speaking to every existing thing in the castle that looks like a snake which would mean visiting every room to see if such a thing even exists.

What I don't have an answer for is how he would know that in order to call the snake he would have to say the exact words "Speak to me, Slytherin, greatest of the Hogwarts four."


How did Tom Riddle come to know about the Chamber and Slytherin's legend and the basilisk? How did he know where it was located when over at least 800 years no one else had been able to find it?

I think he came across about the chamber of secret while researching about the school. It was his first home after all and maybe he was figuring out about the founders possessions and came across something about the chamber. Then he might have guessed the monster is a serpent and used parseltongue to control it and lead him to the door of the chamber.

How did Tom Riddle interact with the basilisk without being killed by the basilisk's gaze?

The most simple answer is he never looked at basilisk's eyes and maybe because he's the Heir of Slytherin it won't affect him (just a guess on that part).

Why did it take 800+ years for Slytherin's "true heir" to be born?

I think his and Slytherin's ideas-pureblood are the highest/muggleborns are not worthy-made him the true heir. Slytherin's ancestors may have descended through time but none of their ideas matched Slytherin's as Riddle's ideas did.

  • 1
    Welcome to SciFi.SE! I've neatened up your answer a little - you need to hit Enter twice for a paragraph break, not just one, and you should put a > symbol before quotes to signify that they're quotes. Anyway, this looks a little speculative - it would be a stronger answer if you could find quotes from canon sources that back up your points. Feel free to take the tour and visit the help center to learn more about the site.
    – F1Krazy
    Commented Jun 20, 2018 at 8:22
  • Welcome to SFF! This is a nicely reasoned first answer but here we encouraged sourced and evidenced answers so editing in any of that will improve this. I've also removed the parts of your answer that seem a bit like a discussion as this is a Q/A site and not a discussion forum, I invite you to take the tour if you haven't already done so!
    – TheLethalCarrot
    Commented Jun 20, 2018 at 8:22

Salazar Slytherin believed that Muggleborns were untrustworthy because they would reveal the location of Hogwarts and all those who were magic to the Muggles who were killing and torturing witches and wizards at the time. Muggles and wizards were at war. That's why he didn't want Muggleborns in Hogwarts. When he was about to leave, he built the Chamber of Secrets and put the Basilisk in it so that if the Muggleborns betrayed wizards and the castle was under danger, it would have a monster to defend it, and Slytherin's heir to control it toward enemies. Do not forget that Hogwarts is a castle, not a palace. There is a reason it was made a castle and not a palace -- wizards were at war and in constant danger of death.

  • It seems that there was no need for the basilisk to be used and for the chamber to be opened and that's why it was never opened before riddle, at least with attacks. Riddle was a phyco, I do not agree in that this was hat Salazar Slytherin created the chamber for, nor his noble work as tm says. After all do not forget Slytherin himself was one of the greatest wizards of time but not a Dark Wizard.
    – lina
    Commented Apr 4, 2014 at 21:37
  • 3
    I think this is almost completely mistaken. I didn't ask about castles versus palaces and you've given me no valid citations for anything you've said. Slytherin was a skilled wizard. He was also a dark wizard. Sorry, but he was. He built the Chamber of Secrets to practice dark magic in, he discriminated against Muggleborns, and he placed a lethal Basilisk in Hogwarts in order to kill people. If you'd like, you can do some research and improve your answer, and I'll reconsider it, but for now: -1 Commented Apr 5, 2014 at 1:36

Corvinus Gaunt himself know the actual entrance to the Chamber of Secrets and has been a student of Hogwarts.

But instead of opening the Chamber he decided to hide it in the girls toilet at the time toilets were established at Hogwarts. The theory that the basilisk was actually an anti muggle defense is in fact great but has a little problem, only a wizard could see the castle.

But I think Salazar Slytherin was actually using old roman water technology of aqueduct when he created the Chamber of Secrets. So I think the Chamber was originally located under a fountain and Corvinus changed this.

Living about the time of 1700 Corvinus Gaunt had a clear problem to create the modification he need a clear excuse. And what better excuse could be if he said that he has been told about a monster in Hogwarts , but knows about a secret Chamber. So he could use the entrance in the girls bathroom actually as an excuse to lock the creature in her secret Chamber. Thats how he could know about the entrance and create the legend but could not open the Chamber.

But the second Parselmouth after Salazar Slytherin was eventually forgotten and no other Gaunt ever attended Hogwarts. Then Tom Marvolo Riddle probably found during his school time a text from Corvinus.Tom Riddle still needed six years to find the Chamber.

The rest is no problem telling the basilisk to close its eyes and bring it under Tom's Imperius Curse.

The case with Ginny Weasley is a simple one too. Under Trance by the Horcrux, the Horcrux simply uses Ginny's body but ordered the Basilisk as a living Tom would do.

Harry's cases is more complicated. At first there are the two Horcrux the Diary and Harry, but the Riddle Horcrux acted like the living Riddle allowing Harry to enter. What Voldemort would not know is that probably all the defense spells which stop others from entering the Chamber were actually bound with the Basilisk.So he lowered them for Harry to enter, but Harry simply destroyed the spells that shield the Chamber by killing the Basilisk. If the Basilisk was dead anyone could enter who speak parselmouth even without knowledge of what it sounds like.

Dumbledore could have tried to have Morfin Gaunt released from Azkaban. Maybe Morfin not only shows Dumbledore his past but also writes for him texts to understand parselmouth in order to help Dumbledore defeating Voldemort. That's why Dumbledore knows what Morfin says, but probably refused to use it by himself

  • 4
    Per the OP: "I'm looking for CANON COMPLIANT explanations for. By "canon compliant", I mean within the spirit of canon, answers directly from the book(s), or quotes from J.K. Rowling." You cite no sources, quote no book or J.K. Rowling. Commented May 4, 2016 at 12:35
  • I would also suggest you break this up a little.
    – Rogue Jedi
    Commented May 4, 2016 at 12:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.