Professor Longbottom was showing his class how to prune a Bolivian Razor Bush without losing any appendages when John arrived at Greenhouse Four. The professor caught his eye and held up a gloved finger, the universal signal for, "Be with you in a moment." John nodded and took a seat in the corner.

The class was made up of Gryffindor fifth years; he knew because he recognized two of them from Quidditch. Sally Donovan was something of a Hogwarts celebrity, having scored the winning goal in a nail-biting match against Slytherin the year before. She was sitting with one of her teammates, a pasty bloke whose name John couldn't remember. Both had looked curiously at John when he entered the greenhouse. So had most of their classmates, but he was startled to realize that the pair were still watching him.

Smiling perfunctorily, he gave them a small wave. The bloke frowned and whispered something in Donovan's ear. She only continued to stare. Suddenly, John wasn't looking forward to the upcoming match against Gryffindor so much.

"Right, I'm going to let you all take a stab at it now," said Professor Longbottom. "Shout if you need me, and remember: safety first."

While his students put on their goggles and gloves and went to work, Longbottom walked over to John.

"How is Mr. Holmes?" he asked quietly.

"Fine, I think," said John.

"Do you know how it started?"

John shook his head. "Sherlock was already bleeding by the time I got there. I did hear one of them call him a smartarse, though."

Longbottom sighed.

"That's what I was afraid of," he said. "Sherlock Holmes is a true prodigy, and prodigies always have it rough, especially when they don't know better than to show off. You should have heard the things people used to say to Hermione Granger."

John could never get used to the way Longbottom would casually allude to his friendships with some of the most famous witches and wizards of the age. If anyone else reminded him that they were old school chums with Hermione Granger, John would think they were deliberately name-dropping. But Longbottom was too modest for that; John only knew the professor was a war hero in his own right because the other students talked about it.

"Actually, Hermione got bullied more for being Muggle-born," Longbottom continued. "At least Sherlock won't have to deal with that."

"That still happens," said John.

Longbottom looked at him curiously.

"I know, John," he said. "I just meant that the Holmeses are a very old wizarding family. No one who cares about that sort of thing is going to mistake Sherlock for a Muggle-born."

"Oh."

John felt his face flush. Of course that was what Longbottom had meant. Why did he have to go and blurt the first thing that came into his head?

It wasn't like John to let his mouth get ahead of his brain, but Longbottom had touched on a sore subject. Wizards and witches loved to talk about how terrible life used to be for Muggle-borns and how much better things were now that Voldemort was gone, as though the death of one person could eradicate prejudice overnight. They were kidding themselves. True, John had never been openly persecuted because of his heritage, but people treated him differently once they found out his dad was a butcher and his mum worked in a dress shop. They found a million subtle ways to remind him that he didn't fit in. Not all of it was malicious, but sometimes the well-meaning comments about how he could pass for pureblood were just as infuriating.

To his relief, Professor Longbottom changed the subject.

"John, we need to talk about how you handled the situation this morning. It was very noble of you to defend Sherlock, but threatening his attackers wasn't the answer. Next time, fetch a teacher."

John said that he would, but he had no intention of keeping his word, and he suspected Longbottom knew it. The professor had been thirteen himself once, and more recently than most of his colleagues. Surely he remembered that being labeled a snitch was far worse than getting detention for fighting. But if he felt compelled to play the responsible adult, then John would humor him.

"How did you get involved, anyway?" Longbottom asked.

John shrugged. "I just happened to pass by and see those Slytherins attacking him. It seemed like the only decent thing to do."

"You're not friends, then?"

"No. I'd never seen him before that moment."

"Oh." Longbottom looked disappointed. "Too bad. If anyone at this school could use a friend, it's Sherlock Holmes."

John was trying to think of an appropriate response when someone began shouting for the professor. He turned just in time to see Donovan's pasty companion fall to the ground.

Longbottom vaulted across the greenhouse faster than John would have thought possible for such a stout man. He followed instinctively.

"Anderson, how many times must I say to be careful?" Longbottom shouted.

John braced himself for an unpleasant sight. He wasn't particularly squeamish, but an accident with something called a Razor Bush had to be exceptionally nasty. He took a deep breath, looked down, and blinked in confusion.

There was not a drop of blood in sight. Anderson was writhing on the ground, his face twisted with pain, but he showed no signs of injury. Longbottom looked as bewildered as John felt.

"What happened?" he asked Donovan.

"I…I don't know," she stammered. "He just fell over. He seemed fine a minute ago."

Longbottom dropped to his knees.

"Anderson…Anderson, can you hear me?"

Anderson only groaned.

Longbottom examined the boy while the class watched helplessly. He checked his pulse, his breathing, his temperature. He even pried open his mouth and looked inside. Then the silence was broken by a gasp.

"His eyes!" shrieked a girl standing next to Donovan. "Look at his eyes!"

John leaned forward and gasped himself at what he saw. Anderson's eyes, which had been pale blue a moment ago, were now blood red.

For one second, Longbottom froze. Then he leaped to his feet.

"John, find the headmistress," he said. "Tell her a student has been…Tell her to meet us in the hospital wing."

John took off without so much as a nod.

As he sprinted up the hill, Longbottom's words replayed in his head over and over. The professor had stopped himself from saying something, and John thought he knew what it was.

Tell her a student has been poisoned.