Every time Harry, Ron, and Hermione pass the third-floor corridor, they check that Fluffy is still there. But Hermione also starts to be preoccupied with the exams that are looming at the end of the year, and the teachers start to pile on more and more homework. One day in the library, Ron notices Hagrid, but when he greets him, Hagrid becomes very shifty and leaves with a book behind his back. They discover that Hagrid is looking up books about dragons, though Ron comments that keeping a dragon as a pet is illegal.
While Harry and Ron have grappled with their own dangerous desires, Hagrid’s deepest desire becomes dangerous as well—both in the sense of what it is, an illegal fire-breathing dragon, and how he acquired it, as it is ultimately revealed that he only gained it in exchange for a piece of key information about how to tame Fluffy.
Harry, Ron, and Hermione decide to go down to Hagrid’s hut. They start to ask Hagrid more about the other enchantments guarding the Stone, revealing that they know what Fluffy is hiding. Hagrid doesn’t tell them, but he does tell them who is helping protect the Stone, including Dumbledore, Quirrell, and Snape. The students think to themselves that if Snape is helping to protect the Stone, he could easily find out how the other teachers had guarded it.
Knowing that Snape likely knows how to get to the Stone is ultimately what prompts Harry and the rest of the gang to try and steal it first. They know that they would be breaking many rules to do so, but their impulse to sacrifice themselves for the good of the community as a whole proves even stronger.
Hagrid assures Harry that he hasn’t told anyone how to get past Fluffy. Harry is relieved, until he sees something on the fire: an enormous black dragon egg, which Hagrid reveals he won the previous night in a game of cards with a stranger. Now, they think, they have to worry about what might happen if Hagrid is discovered with an illegal dragon.
Hagrid’s desire led him to acquire an illegal dragon, but instead of any impulse to try to follow the rules, Harry, Ron, and Hermione’s main concern is instead with protecting Hagrid and making sure that he doesn’t get into trouble.
A few days later the dragon hatches, but when Harry, Ron, and Hermione sneak down to see it happen, Malfoy also ends up following them and seeing the dragon as well. They grow very nervous about Malfoy and try to convince Hagrid to set the dragon free. Hagrid refuses, saying that Norbert (his name for the dragon) is too young to survive on his own. Harry suggests that they send Norbert to Ron’s brother Charlie, who can take care of him and then set him free. Hagrid agrees, and they send an owl to Charlie.
Harry’s decision again prioritizes doing what’s right rather than strictly following the rules. He doesn’t want to turn Hagrid in and he doesn’t want to condemn this dragon to die, but he also knows that they all could get into serious trouble because of what Malfoy has seen.
The following week drags on. Harry, Ron, and Hermione help take care of Norbert (even though he bites Ron’s hand). Then Hedwig returns with a letter from Charlie. Charlie suggests that they send Norbert with friends of his who are visiting him the following week. He writes that they should bring Norbert to the tallest tower at midnight on Saturday, so his friends can take the dragon away under the cover of night.
Getting rid of Norbert now explicitly requires that Harry, Ron, and Hermione break the school’s rules, sneaking out of bed at night. But again, they do so in the hope that Hagrid can stay out of trouble and that the dragon will be in good hands.
By the next morning, Ron’s hand has swollen to twice its size, forcing him to go to the hospital wing. When Harry and Hermione visit him, Ron reveals that Malfoy had come to his bed to make fun of him under the guise of borrowing one of Ron’s books. But Ron then realizes that Charlie’s letter was in the book Malfoy took, so now Malfoy knows about the plan. Still, Harry and Hermione think that they can’t change the plan.
Hagrid’s desire to keep a dragon becomes particularly dangerous when it not only threatens Ron’s health, but also threatens to get Harry, Ron, and Hermione into serious trouble as they try to help Hagrid stay out of trouble.
On Saturday, Hagrid says goodbye to Norbert and Harry and Hermione carry him up to the castle under the Invisibility Cloak. In the hall, they see Professor McGonagall giving Malfoy detention and taking twenty points from Slytherin as he tries to protest that Harry is going to be coming with a dragon.
The Invisibility Cloak once again becomes an instrument that helps Harry and his friends break the rules in a useful way, as it allows them to protect Hagrid from legal ramifications.
Harry and Hermione make it to the top of the tower, where Charlie’s friends take Norbert from them. They are elated that their plan goes so well, and that Malfoy got detention in the process. But as they slip back down the stairs, Filch emerges from the darkness, and Harry and Hermione realize that they have left the Cloak at the top of the tower.
This is one of the rare times that Harry is punished for his rule-breaking, though it is worth noting that this punishment would have been avoided if he had retained his Invisibility Cloak.