The Dueling Club
Chapter 11 of Harry Potter and the Chamber of Secrets: The Dueling Club
By morning, Harry's arm is healed, and he is discharged from the hospital wing. He finds Ron and Hermione in Moaning Myrtle's washroom, already brewing the Polyjuice Potion. Harry tells them about Dobby's visit; Ron observes that if Dobby continues to help Harry, Dobby will likely kill him.
News about Colin Creevey's Petrification has spread, and Ginny, who is in Colin's class, is distraught; also, there is a brisk business in Talismans and other supposedly magical protective objects. Neville, despite being a Pureblood, believing his weak magical ability makes him a target, buys many, claiming, "they went for Filch first."
Harry, Ron, and Hermione elect to stay at the school over Christmas after hearing that Malfoy is doing the same. But the Polyjuice potion is nowhere near ready, and they need to raid Professor Snape's private stores for ingredients. Surprisingly, Hermione volunteers to steal them if Harry or Ron can create a diversion. During the next Potions class, Harry tosses a firecracker into Goyle's Swelling Solution, splattering students. While Snape administers Deflating Draughts to everyone, Hermione sneaks into Snape's office and retrieves Boomslang skin and Bicorn horn. Hermione adds the new ingredients, saying the potion will be ready in a fortnight.
A week later, a notice is posted about a Dueling Club. Reckoning it will be useful, all three troop to the Great Hall, only to find that Professor Lockhart is running it, assisted by Professor Snape. In the first demonstration, Professor Snape tosses Professor Lockhart across the room using the Expelliarmus jinx. Lockhart then breaks students into pairs; Harry is paired with Malfoy, Ron with Seamus, and Hermione with Millicent Bullstrode. Mayhem ensues: Malfoy jinxes Harry before the start signal, but Harry retaliates; Ron's wand misfires, doing something horrible to Seamus. Hermione and Millicent have dropped their wands and are wrestling—Harry frees Hermione from Millicent's headlock. Lockhart suggests just one pair on stage, and selects Neville and Justin Finch-Fletchley; Snape overrules him and suggests Malfoy and Harry. When Malfoy conjures a snake that slithers towards Harry, Lockhart's attempts to eliminate it fails. As it seems poised to attack Justin, Harry yells at it to leave Justin alone. Surprisingly the snake obeys. Justin escapes the Great Hall as Snape destroys the snake. Ron drags Harry out exclaiming, "I didn't know you were a Parselmouth!" A Parselmouth, Harry learns, possesses the rare ability to talk to snakes, and it is what Salazar Slytherin was famous for and why Slytherin House's symbol is a serpent. Now Harry wonders—could he be the Heir of Slytherin?
The next day, Harry wants to explain everything to Justin, but Justin, believing Harry is the Heir of Slytherin, has gone into hiding, fearing Harry would Petrify him for being Muggle-born. Ernie claims Harry was speaking Parseltongue and chasing the snake towards Justin. Furious, Harry stalks out, smacking into Hagrid, who is on his way to Dumbledore's office to report that something is killing his roosters. Leaving Hagrid, Harry trips over a Petrified Justin Finch-Fletchley and finds himself staring at a smoldering and apparently Petrified Nearly Headless Nick. Spiders are fleeing.
Discovering Harry, Peeves sounds the alarm. Professor McGonagall arrives, and assigns Ernie Macmillan to take Nick to the Hospital Wing while Professor Flitwick and Professor Sinistra take Justin. Professor McGonagall escorts Harry to Professor Dumbledore's office.
The dueling club shows Gilderoy Lockhart's continuing ineptness, as he is unable to block Snape's simple spell, control the student duels, or eliminate Draco's conjured snake. By now, we should be wondering whether Gilderoy is a wizard at all, or merely a very good self-promoter. It is curious that Hermione still seems infatuated with him. Snape sees through Lockhart, of course, and Harry observes that if Snape looked at him like he did Lockhart, he would run for cover.
During the dueling club, Harry's ability to talk to snakes is revealed to the school, though readers first saw this when Harry and the Dursleys visited the zoo in Harry Potter and the Philosopher's Stone. We learn here that it is an extremely rare ability, linked only to Salazar Slytherin and his descendants. Given that the school fears "the Heir of Slytherin's" ongoing depredations, this is a major concern, of course. Proof that there is a connection between Salazar Slytherin and Harry could not be any plainer, and Harry, who knows little about his ancestry, is unable to disprove, even to himself, that he could be the Heir. The only mitigating factor is that Harry was absent during the petrifications. Harry knows this, but is unable to prove it.
This whole episode throws Harry into confusion. The Sorting Hat had wanted to place him into Slytherin House; he plainly remembers that the only reason it did not was because he asked not to be. Obviously, the Hat detected the link to Slytherin that is now made manifest by Harry's Parseltongue ability. Though Harry loves Gryffindor, is he there under false pretenses? This uncertainty, to a greater or lesser extent, will likely prey on Harry at least until the book's end.
Hermione's ongoing unbending is also shown when she raids Snape's stores. Her willingness to break the rules is hardly surprising to readers, who have seen her gradually grow more pliable through this and the previous book; however, it is quite a shock to Ron, who clearly continues to believe that Hermione is entirely rule-bound, despite increasing evidence to the contrary.
Also, Neville's fearing that he may be targeted, even though he is a pure-blood, is probably justified. The series increasingly parallels real-life history, including totalitarian rulers, particularly Nazi Germany. Even within their own society, it was common practice to weed out those considered as "undesirables", including the aged, infirm, or anyone with physical or mental handicaps, leaving only the fittest and healthiest to pass on their "superior" genes to the next generation. If Voldemort should ever return to power, it seems likely that in addition to his strict "pure-blood" ethos, he would only recruit the strongest, brightest, and most magically proficient wizards for his new order. Neville, and other "unworthy" pure-bloods, could become victims under such a regime.
- Why does Hermione have Harry and Ron create a distraction in Snape's class? Was it successful?
Further Study 
- Why does Lockhart start a Dueling Club? What does his performance in it say about him?
- Why was Harry paired with Draco?
- Why was Ron allowed to duel with a known faulty wand?
- How could Harry be unaware he was speaking snake language?
- Is Neville right to be concerned that he might be Petrified, even though he is a pure-blood? Explain.
- Why would a ghost be Petrified?
- Why is Ginny so upset when Colin is Petrified?
- What might be killing Hagrid's roosters and why?
- What evidence is there for and against Harry being descended from Salazar Slytherin?
- Consider what we know at this point about Salazar Slytherin's beliefs, and Voldemort's. Is it possible that Voldemort could be an heir of Slytherin's?
Greater Picture 
Colin Creevey is the first student who is Petrified. His being Ginny's classmate is sufficient reason to cause her distress, but her concern is actually the slowly-dawning realization that she may be responsible, as she was unable to remember what she was doing when it happened, or on the earlier occasion when Mrs. Norris was attacked. We have no way of realizing this at this point; all we know is that Harry was not present at either earlier petrification, or at the double petrification that happens in this chapter. The final attack will largely prove his innocence; but that does not occur for several months yet.
The wrestling match between Hermione and Millicent Bullstrode is useful to our plot, as it is here that Hermione collects a hair she will use in her Polyjuice Potion portion. This will turn into a disaster for Hermione, as the hair is not Millicent's.
Harry again observes spiders fleeing the scene of the latest activity by the monster in the Chamber. This will provide an important clue for Hermione, who will determine what the monster is, but will be struck down before she can pass that information to Harry and Ron. Hagrid's roosters being killed will also form part of that pattern.
In Harry Potter and the Deathly Hallows, it is learned that Harry's ability with Parseltongue is due to a link with Slytherin; it will be a sideways link, though, as it is related to Voldemort's soul shard that adhered to Harry and remains within him. Voldemort is, in fact, the last living heir of Slytherin, through his mother's father, Marvolo Gaunt. The author has confirmed in a later interview that Harry's parseltongue ability vanished when that soul shard was destroyed, and he has not missed it since.
Dumbledore later quiets Harry's doubts by showing him that the sword he retrieved from the Sorting Hat was Godric Gryffindor's. "Only a true Gryffindor could have pulled that out of the Hat, Harry." While Dumbledore likely already knows about Voldemort's soul shard within Harry, it is something he believes Harry is unprepared to hear about yet. It is only at the end of Harry's fifth year that Dumbledore finally reveals the prophecy to Harry, which states that either he or Voldemort must die. Dumbledore, however, understands that Harry will have to die in order to destroy the soul shard he carries; Dumbledore believes, probably correctly, that, at age twelve, Harry is too young to carry that destiny's weight. Dumbledore actually never reveals the soul shard's existence to Harry, instead passing that task to Snape before his death, and charging Snape to conceal its existence until Voldemort realizes his Horcruxes are being destroyed.
- In a later book, Snape notes that some quantity of Bicorn horn and Boomslang skin are missing from his private stores, and suggests that Harry might have stolen them. Harry cannot answer this charge, knowing that Hermione had stolen these ingredients from him two years earlier. We later learn that Barty Crouch, Jr. had been making Polyjuice Potion for his own disguise, and surmise that the theft Snape is talking about was, in fact, not Hermione's past activities but Crouch's more recent ones.
- Note Harry's confusion in this chapter; Harry tells the snake to leave Justin alone, and is confused by Justin's response. Harry is unable to perceive that he has spoken in anything except English, and so doesn't realize that Justin did not understand what he was saying to the snake. Harry's inability to tell the difference between English and Parseltongue is a key point in this book, as he perceives the Monster's voice at several points and does not recognize that the Monster is not speaking in English. Harry's ability to speak to snakes is first seen in the first book of the series, and no mention is made there of whether Harry perceives that the snake is not speaking English. This confusion will reappear later in this book, when Harry has a need to speak Parseltongue and finds it difficult to switch, and will be a minor plot point in the final book.