"Can't we get some things that'll determine motive?" demanded James, striding up and down the room. By now he had rumpled his hair so often and so violently that it might have passed for a bird's nest. "That mirror thing, that's brilliant. Figure out why they're after it, and if they want to protect it or something, fine, have at it, but if they want to steal it, no dice. Don't just gauge magical talent! I mean, any kind of person can fly a broomstick or win at chess, that's kid stuff. Let's do more of the mirror type deal!"

"What, exactly, do you recommend?"

"What about the Sorting Hat?"

"I beg your pardon?"

"I know it's mostly got one function, but it's equipped with some insanely powerful legilimentic spells. It could find out in a snap what someone was after. Or…or…what about this? That idea you had for Arbutus to cook up is good. All the stuff you come up with is all right. But, what if…"

The moment they stepped over the threshold into the next room, the door slammed shut and locked, and when Malfoy dropped a broom and grabbed the handle to see if they could get back through, he immediately leapt back again, cursing.

"Hot!" he yelped. He clenched his fist and started blowing on it. "Hot hot hot hot!"

"I guess we're not supposed to go back," said Harry. "Let's try the other one." He crossed the room, pulled out his handkerchief, wrapped it around his hand, and gingerly touched the handle of the opposite door. When the handkerchief caught on fire, he dropped it.

"Not that way either," he said.

"My hand's going to burn off!" yelled Malfoy.

"Let me see," said Hermione.

"I can't move my fingers! I'm dying! They're going to have to cut it off! That bloody handle was hot!"

"I said, let me see," said Hermione. She took his hand.

"Don't touch it!" he shrieked. She rolled her eyes and pried his fingers off his palm one by one, with accompanying screams and wails.

"For goodness's sake," she said, looking at his hand. It was pink and shiny, and bore the slight imprint of the door handle. "It's just a little burn," she said. "It's no worse than if you'd touched the top of a stove. Er…the side of a hot cauldron."

"But it hurts!"

Hermione twirled her wand and pronounced some kind of complicated incantation. "This will help. It won't heal the burn, though. You have to remember not to do anything with that hand."

"But that's my wand hand!"

"Oh, don't be such a baby," said Hermione. "You'll just be like one of those cricket players who train themselves to use their other hand."

"Cricket?"

"Never mind. Harry, you left Ron the other broom, right?"

"Huh?" Harry hadn't been listening at all. He was staring at the table in front of them, deep in thought. "Oh. Yeah, it's by the door. Er…I'm thinking this one is Professor Arbutus's."

A row of seven bottles sat in front of them, different sizes, different colours, none of them labelled. Harry opened one and sniffed it before Hermione could protest.

"Odourless," he said. "It could be iocane for all we know."

"That's not a real thing, Harry," said Hermione. She picked up a scroll lying on the table and looked over it.

"Who says it isn't?"

"What's iocane?" asked Malfoy.

"Never mind, Malfoy," said Hermione. "It could be poison, though, Harry. Three of them are, according to this."

"What is that?"

"It's a sort of logic puzzle," she said. She began walking up and down, pointing at different bottles and muttering to herself. "Three are poison, two are bubble juice. One is a simple curative, for burn treatment. The other one's something called a burn insulator."

"Oh, brilliant!" said Harry, suddenly excited. "That was in chapter nineteen in our textbooks, you remember? Some people use it to walk through fire or over hot coals, but most people just use it for Potion-making and cooking. Massively difficult to brew, extremely expensive to buy, I'd love to get my hands on it and see if I could replicate…"

"Snape," said Malfoy, "I believe we need to use it."

"What? Oh. For the door handles. But only one of us will have to drink it, we can just hold the door open for the others, right?"

"No good, Harry, the door only lets one person through at a time, it's got a Hominem Revelio charm on it."

"Which one's the curative?" Malfoy asked. "Your bloody spell didn't help much."

"It's just a matter of logic, this parchment's given us all the clues we need to work out which is which, just give me a minute and neither of you talk, that means you, Malfoy, I don't care how much it hurts, don't say anything."

She took the potion out of Harry's hand and set it back down in the empty spot, then gave him a slight shove to get him out of the way and went on pacing, muttering and pointing. Finally she picked up two bottles and tossed one at Malfoy.

"Here," she said. Then she held the other bottle up to the light and looked at it critically. "Do you think there are three doses in here?" she asked.

"Sure. You only have to take a few drops; it's an incredibly effective potion. Professor Arbutus told me once that you could give a drop to a baby and boil him in a cauldron for an hour and he'd come out with only second-degree burns."

"How and why on earth would you test something like that?" Hermione exclaimed, aghast. "Never mind. Here, Harry, go ahead."

"You're sure this is the right bottle?" Malfoy asked when Hermione had taken her drink and handed him the potion.

"Well, Harry and I are alive. At worst, it's bubble juice, and it doesn't taste like bubble juice."

"What if it's a slow acting poison?" Malfoy asked, panic mounting.

"Oh, for goodness's sakes, Malfoy. The curative worked, didn't it?"

"What if it was by luck? You had a one in seven chance. Anyway, why can't I just open the door and then use the curative?"

"Your hand will shrivel up completely if you attempt to turn the handle. You can stay here forever or you can drink the potion."

"Don't drink too much," said Harry. "We might need to get back and I was hoping there'd be some left over, we could take it with us and I could study it."

Malfoy sighed heavily and, with exaggerated care, dispensed three drops onto his tongue.

They filed through the door one at a time, none of them receiving so much as a hint of a burn.

"See, I told you," said Hermione.

"You're just so sure of yourself, aren't you," said Malfoy. "I saw that riddle; it's not like it was even particularly difficult…"

"Shut up, Malfoy," said Harry.

"All I'm saying is that just because she got a couple of…"

"No, I'm not kidding, shut up," hissed Harry.

His tone made Malfoy look up, and then all three of them stood perfectly still.

At the other end of the chamber, blocking the door, sprawled a gigantic troll, even bigger than the one Harry, Ron, and Hermione had faced at Halloween. It was huge, it was ugly, it was—currently—dozing. The smell almost overpowered them; Harry lifted the collar of his pyjama top and put it over his nose.

"I don't suppose there's any chance of moving it out of the way without it waking up?" Malfoy whispered, his voice strained from pinching his nose.

"We could try, but I don't think any of us wants to get that close," said Hermione. "I can hardly breathe."

"Don't you know any smell-blocking spells?" Harry asked.

Hermione wrinkled her brow and thought furiously. "No, I don't think so."

"Hang on, what about when Fred jinxed Percy last month and he couldn't smell or taste anything for two days?"

"Oh, that's just Olfactor Obstructo, but that's a hex, it doesn't get rid of the smell, it only makes you not smell it…"

"Oh, then that won't work at all," said Malfoy, throwing his hands up in the air.

"I'm not sure what the countercurse is, though, I think if Finite Incantatem worked then Percy would have done it, but maybe the person who performed the spell has to do it…"

"Hermione, at this point I don't care if I lose my smelling permanently as long as I can stop Potter from getting that Stone," whispered Harry.

Malfoy looked alarmed. "I do," he said.

"Shut up, Malfoy," said Harry. "Just do it, Hermione, we can't fight if we can't breathe. Everyone get your wands ready, and put the brooms where we can get at them if we need to."

When their noses had been appropriately blocked, they advanced slowly.

"Hermione, you're the best at defensive magic, so keep your wand trained on it in case it wakes up. Malfoy, you and I are just going to try to move it. Can you do Mobilicorpus? It's going to need two of us…"

But they had barely lifted the monster an inch off the ground before Hermione gave a warning cry. The creature roared to life and the enchantment instantly failed, causing him to crash to the ground.

"Who dat?!" he said in a booming voice, looking around. He looked at the three children and his brow furrowed. "Who yer?" he said. Harry, Malfoy, and Hermione glanced at each other. The troll made no move to raise his club.

"Er," said Harry. "We're students. Please don't kill us?"

"I guard troll," he said. "I ax qu…qu…ting I ax."

Harry's eyes darted to the club in his hand. "Er, you ax things?"

"Yup. I ax who yer, wut yer do. Qu…qu…."

"Questions?" Hermione suggested.

"Dat. I ax dem. Who yer, wut yer do?"

"Er, my name is Harry Snape," said Harry, "and we're after the Philosopher's Stone."

"Fer wut yer want?" the troll asked.

"We're trying to protect it," said Harry.

"Oh. Dat good. Fer wut yer want?" the troll asked, looking at Hermione.

Hermione's eyes were round. "It's fascinating," she said. "I never thought mountain trolls were capable of more than a few words in English, this one seems to have grasped basic syntax and everything. In Fantastic Beasts and Where to Find Them, it says…"

"Wut yer want rock?" the troll repeated.

"I want to protect it from Professor Potter, I think he's going to steal it," said Hermione.

The troll scratched his head, but nodded. "Dat good. Wut yer want rock?" he asked, looking at Malfoy.

"I want to steal it to get immortal life," said Malfoy. He looked suddenly horrified.

"Yer wut?!"

"I don't think he has a concept of a joke, Malfoy!" Hermione yelped. "He's not that smart!"

"That wasn't what I meant to say!" Malfoy scrambled backward. "I didn't mean that!"

"Der magic water work!" the troll roared. "Yer say yer wan steal! I KILL! I SMASH! I EAT!"

"Oh no!" said Hermione.

The trolls swung his massive club. Hermione and Malfoy ducked and it whizzed over their heads; Harry jumped and it went under his feet and skidded on the stone floor before the monster heaved it up again and charged directly at them.

"What does he mean, magic water?" Malfoy shouted, leaping to the left as Harry leapt to the right and Hermione ducked between the troll's legs.

"Veritaserum!" said Hermione. "There was Veritaserum in the burn insulator!"

Malfoy swore and ducked under the wildly swinging club.

"Veritaserum? That truth thing?" said Harry. "Good going, Malfoy, you've screwed everything up…"

"Watch out, Snape!"

Harry turned just in time to see the troll's massive fist about to crash down on his head. He jumped awkwardly out of the way and the troll smashed down on the ground, losing its balance and rolling over itself.

"Stupefy!" Malfoy yelled, but the curse bounced right off the troll's thick skin and dissolved in the air.

"Together," said Hermione. "One, two, three…"

She and Malfoy shouted "Stupefy," but the jinx rebounded again and this time they had to duck as it shot over their heads.

"You're just making it mad!" shouted Harry as the troll rumbled to its feet, roared, and charged again, proving his point. "Malfoy, you idiot, why can't you just give up on stealing that Stone?!"

"Are you kidding? Infinite life? He's moved, get to the door!"

The three of them tore for the door; Harry, who got there first, yanked on it.

"It's locked," he moaned.

"YER NO GO DOOR!"

This time the troll did hit them, carrying them all off their feet with one swipe of his club.

"We're all gonna die," Malfoy wailed.

"Where's the key?" Hermione gasped.

"Watch out for the club!" Harry yelled.

They tore away again, toward the other door, but upon reaching it found that it, too, locked from this side.

"They're trying to kill us!" gasped Malfoy.

"Well, if you didn't want to live forever, you wouldn't be about to die! Go left!"

"I can't help it! Everyone wants to live forever!"

"Oh, don't be ridiculous—there it is, Harry, it's on his necklace!"

Harry squinted at the troll, and, sure enough, around the massive wobbly neck on a leather cord hung a miniscule key.

"Good eyes, Hermione! How do we get it?"

"Try and jump on its back, the way you did with the other one! Malfoy, the only people who want to live forever are people who haven't thought it through!"

"Oh, believe me, I've thought it through. For example, did you ever think about selling years? Favours in exchange for elixir? And that way you could keep everyone you like alive as well!"

"That would be awful! Get behind it, Harry, and then jump! I mean, imagine, you'd be in complete control of everyone's lives. People would be sucking up to you on the one hand and planning to kill you on the other hand, and you couldn't ever make any real friends, imagine how lonely."

"If you could live forever you wouldn't need friends, you could do everything you ever wanted! You could travel the world, read all the books in the library, I'm sure that would appeal to you…"

"I can't get behind him, Hermione, he moves too fast!"

"Run underneath him!"

"Are you kidding? Even with that jinx I can barely breathe!"

"Hold your nose! But you wouldn't do everything, Malfoy, you'd just go on doing the same things you always do, like when you promise yourself you'd do the assignment if only you had a few more days and then you get a few more days, don't let it step on you!"

"I'm trying, I'm trying!"

"No," said Malfoy, "but if you had forever you would have forever!"

"Not really, the Stone's bound to get lost or stolen at some point, what do you think we're doing here? Hey, stinky, over here! Look at me! Hey, hey! Don't pay attention to Harry! Over here! This is the guy you want to smash…"

"Don't lead him toward me!" said Malfoy. But the troll had turned and was now lumbering in his direction. Malfoy looked around wildly, saw the broom in his hand, and jumped on it, flying up and out of the troll's reach. "Nyaah," he said, sticking out his tongue.

"Harry, you get on your broom too!" Hermione shouted. "One of you distract him and the other get the key!"

"If you had infinite money," said Malfoy, diving toward the troll in a blur, "you could hire protection."

"Like fifteen-foot mountain trolls? No, wait till Harry distracts him or he'll just…!"

The troll roared and reared back. Malfoy's hand, reaching for the key, was knocked back.

Harry soared up and circled the troll three times, making its eyes roll in its head.

"Go for it, Malfoy!"

"Any protection you hire," Hermione went on doggedly, "someone can get through. And you'll always be terrified that someone will take it and—watch out for his hand!"

The troll grabbed the end of Malfoy's broom as he zipped by again.

"JUMP!"

He jumped, flailing, off his broom and managed to kick the troll in the nose. The troll grunted and released Malfoy's broom, which floated off toward the ceiling.

"Granger, give me yours!"

"Hang on, let's try and levitate the club, you remember, Harry? If we can knock him out we can get the key! On three, ready? One, two, three…"

"Wingardium Leviosa!"

The club spun up into the air.

"Release!" shouted Hermione. The club came crashing down beside the troll and struck Malfoy on the foot. He shouted in pain.

"Well, that didn't work," said Harry. "You two to the left, me to the right, jump!"

"I can't jump I have a fifty kilogram club on my foot oh help oh help get it off get it off!"

"What good," panted Hermione, tugging on his arm, "is living forever if you're afraid all the time? That's not really living! Especially if you don't have any friends!"

"Everyone would love you!" Malfoy gave the club a tremendous kick and leapt, right into the troll's fist. He was able to roll away, but he had a cut on his eyebrow. "Ow!"

"Think about it. Do you love Nicolas Flamel? Would you love Potter if he got it? No! You'd be nice only until you could stab them in the back and steal it—you've got blood on your forehead. Episkey. Stand still, will you?"

"No, I won't, there's a fifteen-foot mountain troll about to smash me!"

On hearing the word "troll," the troll roared and charged at Harry and Hermione. Harry froze the ground in front of him and he slipped and fell on his nose.

"Not bad," said Malfoy. "When you're rich and immortal you don't need friends, though! I said that! Quick, while he's down—" But he was up and madder than ever. The boil on the end of his nose had turned purple with rage.

"What about family, then? Don't you have parents? Episkey! There!"

"Er, well, I would give them the elixir—"

"That's not the point! What if they don't want to live forever? What about all their friends and their friends and family? Would you give the elixir to everyone? No one would die and the world would get overpopulated! What if one of them did one thing you didn't like six hundred years from now and you let them die and then regretted it for the rest of your immortal years because it was your fault you killed them! What if…?"

"Hermione, watch out!"

The warning came too late. The giant greenish fist grabbed Hermione, pinning her arms to her sides; it lifted her up in the air and began to crush her. Her wand fell to the floor with a tinkling sound.

"Stop! Stop! She's not the one!" yelled Harry. "Let her go!"

"I SMASH! I EAT!"

"Malfoy, do something!"

"What do you want me to do?"

"I don't know!"

Harry watched in horror as Hermione headed for the troll's mouth.

"Hermione, what do we do?"

She writhed and her face turned purple, but she gasped out an answer almost immediately. "Waddiwasi!" she squeaked. "Use Waddiwasi, someone!"

"Oh, of course!" cried Malfoy. "Waddwasi!"

With the force of a bullet, the club shot from the troll's hand and smashed him in the head. He toppled, loosened his grip in Hermione…

"No!"

Being dropped from a height of twelve feet isn't a big deal, normally. Unless of course you're being dropped on your head onto a stone floor. Like Hermione was.

The troll crashed down. Hermione landed with a sickening crack and Harry raced over to see if she was all right.

"Don't know why I didn't think of waddiwasi sooner," muttered Malfoy. "Would have saved us a lot of trouble."

"She's breathing," said Harry. "I think she's just out. We have to carry her…"

"Are you kidding? Who knows what could be further on? We can't even risk a mobilicorpus on her! And that troll could wake up at any moment, come on, let's get the key…"

"We can't just leave her here, in a room with a troll who could wake up at any time! And I don't know that protective spell!"

Draco sighed. "Fine. Put her over there, I'll put some protective spells around her."

Harry healed the head wound as best he could so that she wouldn't bleed to death while they were gone; Draco enchanted her entire corner with the strongest spells he could muster and showed Harry how to reinforce them, and then they hurried across the room, picked up their broomsticks (Draco left the floating one with Hermione, citing "she's a lousy flier, anyway" as his justification) and fit the key into the lock.

"Malfoy," said Harry suddenly.

Draco glanced at him.

"Er…thanks, for all that," said Harry.

"Eh?"

"For…you know, helping. And everything."

Draco shrugged. "Whatever," he said.

But from that moment on, Draco Malfoy became his friend. There are some things you can't share without ending up liking each other, and knocking out a fifteen-foot mountain troll is one of them.