Harry Potter and the Methods of Rationality

Without those compasses they might have searched for days and never found each other, which was a territorial hazard of fighting in the upper levels of Hogwarts.

Draco had a bad feeling about what would happen when Dragon Army found the Chaos Legion. Harry Potter had changed since Bellatrix Black had escaped; the Heir of Slytherin had begun to seem truly Lordly now (and how had Professor Quirrell known that would happen?) Draco would have felt a lot better with Hermione Granger standing alongside him with her twenty-three Sunshine Soldiers in tow, but no, the Sunshine General was being stupidly proud and refusing to accept aid against General Potter. She wanted to take down Potter herself, she'd told him.

The Noble and Most Ancient House of Malfoy had maintained their influence over Britain for centuries by understanding that you couldn't always be the most powerful. Sometimes another Lord was just stronger, and you had to settle for merely being his foremost lieutenant. You could build up quite a position of wealth and power over a dozen generations of being second in command. You just had to be careful, each time, not to let your House be dragged down with the fall of the Lord you served. That was the Malfoy tradition which centuries of experience had honed...

And so Father had thoroughly explained to Draco that if he ran into someone who was obviously stronger than him, Draco was not to resent this and not to deny it and not to throw a tantrum that could sabotage his potential position, but Draco was to make sure that his place in the next generation's power structure wasn't any lower than second.

Granger, apparently, had never gotten this lecture from her own parents, and was still in denial about the obvious fact that Harry Potter was becoming stronger than her.

So Draco had secretly met with Captain Goldstein and Captain Bones and Captain Macmillan and they'd agreed to all do their best to make sure that Dragon and Sunshine didn't engage each other before they engaged the larger threat of Chaos.

It wasn't really violating the agreement against traitors, you weren't soliciting traitors if you honestly meant to help the other army.

A high ringing tone belled through the corridors to signal the start of the battle, and a moment later Draco shouted "Go!" and the Dragons started running. It would tire his soldiers, it would cost them something even after they stopped and caught their breath, but they had to put Chaos directly between themselves and the Sunshine Regiment.

Harry and Neville walked at a leisurely pace through the corridors, Harry watching the yellow-golden compass that pointed toward the location of the Sunshine Regiment, and Neville keeping a lookout just in case they ran into someone else.

Their footsteps sounded a bit thumpy, if you listened closely.

"So," the Chaotic Lieutenant said after a while. "That's why you had us practice dueling with all that weight strapped on?"

Harry nodded, keeping his eyes on the compass that led to Sunshine; if the apparent direction started to change quickly then they were getting close.

"I didn't want to say anything in front of the others, but a couple of weeks isn't a lot of time to put on extra muscle," said Neville. "And the balance is different, and I think this weighs more actually, and doesn't this count as Transfiguring a Muggle artifact?"

"Nope," Harry said. "I checked that in advance. You can see it in Hogwarts statues, so some wizards used to wear it, even if they were just being fashionable for the Dark Ages." And since nobody would ever try this if they weren't fighting first-year students using weak spells like the Sleep Hex, it didn't count as giving away good ideas, either.

They came to a Y-intersection, an annoying one; neither corridor bent in quite the right way to take them on a direct intercept course toward where Sunshine would go as they followed the Chaos Legion following Dragon Army. So Harry chose what seemed like the better of the two options, and Neville followed.

"We'd better try a quick Silencing Charm on this stuff when we get close," Neville said. "It's kind of noisy, they might figure it out."

Harry nodded, and then said "Good idea" in case Neville hadn't been looking at him.

They trudged on through the stone-floored corridor of the upper reach of Hogwarts, lit by windows of plain glass or stained glass, now and then passing statues of witches and dragons and even the occasional wizard-knight in plate armor or chainmail.

The Sunshine Soldiers were striding through a long, wide corridor with their wands out and pointed. They couldn't use the Prismatic Shield while they were maneuvering, but Parvati Patil and Jenny Rustad were currently maintaining Contegos around the officer group, who would be the first targets of any ambush.

Their tactic for the next battle, she and her officers had decided, would be to mix directly in with the enemy soldiers as fast as possible - after having practiced among themselves how to support one another, avoid hitting each other, and get into positions where enemy soldiers would hesitate to fire. They'd only gotten in four hours practice, but she thought her troops would already be better at that kind of mixed-in fighting than soldiers who hadn't practiced at all. It seemed like the sort of tactic Chaos would use, but they hadn't actually used it yet.

It was a good strategy, she believed. And yet still, no matter how much she'd lectured her soldiers, they'd persisted in whispering fearful rumors about what Harry and Neville were learning to do. Finally she'd gone off and talked with Captain Goldstein, who understood things like Troop Morale, and Anthony had suggested -

"That's weird," Captain Macmillan spoke up suddenly, frowning at the fiery and iridescent compasses he held in either hand. (Ernie was, as Harry would have termed it, "good at spatial visualization", and so had been designated to hold both compasses and try to figure out what their enemies were doing.) "I think... Dragon's not moving fast anymore... I think they got on the other side of Chaos from us first... and it looks like Chaos is moving to attack them instead of trying to maneuver out from in between?"

Hermione frowned, trying to understand, and she saw similar frowns on the faces of Anthony and Ron. If Chaos and Dragon attacked each other straight out, and spent all their forces fighting each other, that was practically conceding the battle to Sunshine...

"Potter thinks we're allied so he's attacking Malfoy now, before Dragon can link up with us," said Blaise Zabini from the common ranks of soldiers. "Or Potter just thinks he can beat both armies in a row, if he attacks them separately." The Slytherin boy gave a condescending sigh. "Are you going to promote me back to officer now? You lot are hopeless without me, you know."