By breakfast, Ron had written his entire contribution to saving the world on the back of a Chocolate Frog card. He showed it to Percy with the grim pride of someone presenting a particularly unpleasant shopping list.
"Two pulls, stop. Three, come back. If the water climbs the wall, put the stone down. If anybody sounds like my mum, put the stone down harder."
Percy examined the card. "That last one's going to make Christmas awkward."
"Christmas can complain when we get there."
Hermione reached across the table, turned the card over, and checked that Ron hadn't written anything on the picture itself. The wizard on the front objected to being used as emergency equipment, which Percy thought was rich coming from a man whose most famous achievement involved accidentally swallowing a cauldron.
Harry sat beside them with both hands around a cup he hadn't drunk from. He looked tired, but when Percy asked about his scar he answered before Hermione could reach for her notes.
"Quiet. I'm not going to poke it to check."
That sounded enough like Snape to make all four of them uncomfortable. Ron pushed a piece of toast across the table, and Harry ate it with the expression of someone proving a point to several people at once.
They left before the hall filled. Outside the windows the lake lay flat and grey, with nothing breaking its surface to suggest that an enormous ancient creature was waiting beneath it for three children to attempt an inspection nobody could properly explain.
Percy kept his attention on his shoes. Yesterday, reaching for the stolen part of himself had felt natural enough that he could still remember the movement without trying, and that was exactly why he wasn't going to repeat it.
At the western stair, Professor McGonagall checked their equipment herself. She tugged every knot, examined both ordinary oil lamps, and made Ron demonstrate how the slab dropped into its groove without putting his fingers underneath it.
Professor Flitwick had attached the safety rope to an iron fastening well above the water channel. The rope carried no charm beyond a small light at the upper end, where any magical interference would be visible before it reached the people below.
"The knots are ordinary," he told them. "I have been tying them considerably longer than I have been teaching."
"Comforting," Percy said. "I was worried we'd die because of extracurricular macramé."
McGonagall looked at him. He tightened his own knot and decided that silence was also an excellent survival skill.
Dumbledore stood beside the blocked channel with his wand lowered. He repeated the limits without making them sound negotiable: they would inspect the chamber, identify the return passage if possible, and withdraw before making any offering to the seal.
Harry looked directly at him. "Even if it tells us this is our only chance?"
"Especially then."
Ron positioned himself beside the slab. Hermione watched him settle the wooden wedge into place, then deliberately turned away from the marks cut into the arch; they had covered those with cloth last night, and nobody was going to make Ron remember what lay underneath it.
Percy went first with one lamp. Harry followed, Hermione came last, and the rope slid through Ron's hands in short, controlled lengths as the upper passage disappeared behind them.
----------------------
The stairs were older than the castle and worse at pretending to be convenient. Every seventh step was shallow enough to catch a heel, and the walls narrowed until Percy had to turn his shoulders to keep the lamp from brushing stone.
Water moved in a groove along their left side. It should have been descending with them, but at irregular intervals a thin ridge travelled uphill, flattening only when it reached the darkness above.
Percy watched without touching it. He could feel the lake beyond the stone, vast and familiar, and beneath that the gate was a place his senses wanted to slide around rather than enter.
"Still yours?" Harry asked quietly.
Percy knew he meant the other pressure. "Still there. I'm leaving it there."
Hermione counted the next twelve steps under her breath. She was avoiding the rhythm of the water, and Percy recognised the trick because he was doing much the same thing with the squeak of Harry's trainers.
The passage ended at a low doorway. Beyond it their lamplight opened over a round chamber with no furniture, no convenient altar, and no giant message explaining which part would kill them first.
"Bit bare," Percy said. "I'd leave a terrible review."
Three shallow hollows surrounded a central depression in the floor. Grooves connected them, but the pattern wasn't a triangle: each hollow had its own narrow path leading back towards the doorway, and all three paths met only after crossing the threshold.
Hermione knelt without putting her hands on the stone. Harry stopped beside her, his gaze moving between the grooves and the water channel entering along the wall.
"They don't meet inside," he said. His finger followed the empty space between them.
"No." Hermione shifted the lamp until the shadows shortened. "We assumed the return was part of the same exchange. It may only become one after we leave it."
Percy felt a distant weight shift under the lake. Aequor wasn't speaking yet, but the attention was unmistakable, like standing on a dock beside something too large to see all at once.
He sent a thought no more complicated than a question. The answer arrived as a pressure against his palms and a memory of waves drawing back from a beach, leaving separate trails that joined beyond the sand.
"He thinks we're looking at the right bit," Percy said. "Or he wants us to go to the seaside. His instructions could use subtitles."
Hermione didn't smile. Her eyes had found a row of marks just inside the central depression, and the muscles around her mouth tightened before she deliberately looked away.
"The words are easier here," she said. She tucked both hands beneath her arms.
Harry moved his foot between her and the inscription. It wasn't much of a barrier, but the interruption made her blink and take a proper breath.
"Easier to understand?" Percy asked.
"Easier to finish. I can feel where the next line should go."
Nobody needed that explained. Percy gave the rope two pulls, waited for Ron's answering tug, and set his lamp down well away from the channels.
"Then we look at the plumbing. Plumbing doesn't usually demand a dramatic reading."
Harry crouched by the nearest return groove. A thin brown deposit edged the stone, but one section near the doorway had been worn smooth by something heavier than water, and he followed it until his fingers stopped above a shallow ridge.
"Something's meant to slide across here."
Percy examined it from the other side. The ridge was actually the edge of a narrow stone tongue recessed into the floor, with a thumb-sized gap where it could be lifted from the passage rather than the chamber.
The upper sluice kept the water out. This smaller piece, if raised, would block the three return grooves together.
Hermione looked back up the stairs. "The person outside doesn't just pull us out. They keep this open while the return passes through."
"So if the big stone goes down too soon," Harry said, "does this stop as well?"
Percy pictured Ron holding the slab, ready to obey the first sign of trouble. The instruction had sounded wonderfully simple upstairs, which was apparently why the universe had decided it needed work.
They inspected the connection without moving anything. A narrow slot ran beneath the left wall, linking the small tongue to the channel above through a sequence of stone levers that Percy could just see when he lowered the lamp.
"We go back," he said. He reached for the lamp.
Hermione turned towards the centre again. For half a second her expression suggested an argument, and then she pressed her lips together and stood.
"We go back."
----------------------
They had reached the fourth step when the lamp behind them went blue. Percy looked over his shoulder and found a thread of water crossing the chamber floor against the slope.
It wasn't coming from the lake. It was seeping out of the hollow nearest his abandoned lamp, forming a bright bead where there had been dry stone a moment earlier.
His first instinct was to call it over. The familiarity hit before thought, the easy certainty that water would answer him, and he had already lifted his hand when Harry caught his wrist.
"You said you weren't reaching."
Percy froze. The bead trembled, and somewhere impossibly far away a pressure answered the movement he hadn't finished making.
He lowered his hand. "Thanks."
The water flattened into a shape too neat to be accidental. For one horrible instant Percy saw the outline of a kitchen window, blue curtains moving in a breeze he couldn't feel, and the suggestion of somebody turning from a sink.
He knew that kitchen. It had never existed anywhere in this world.
"Percy?"
Hermione's voice was close and real. Percy fixed his eyes on the soot mark above her lamp and counted the cracks in the glass until the urge to look past her stopped feeling like his own decision.
"Don't look at it," he said. "It found something."
Harry's grip tightened rather than pulling. That helped more than an order would have, and Percy took one step upward under his own power before another bead of water appeared in the hollow.
The first bead jerked sideways. The picture broke, the blue flame returned to yellow, and a sharp pulse struck Percy's senses from the direction of the stolen sample.
For a moment he felt metal biting into something it couldn't hold properly. Then the sensation vanished, leaving the chamber colder than before.
Hermione had seen the interruption too. She kept climbing while she spoke, choosing her words between careful breaths.
"Someone adjusted it. The image stopped when they did."
"Brilliant," Percy said. "Our terrible escape route comes with technical difficulties."
He wanted the joke to sound normal. It came out thin, but Harry let go of his wrist when Percy took the next step, and that was enough to keep him moving.
At the bend, the rope tightened twice. Ron was asking for a stop, and Percy halted so quickly Hermione nearly walked into Harry behind him.
A scrape came from above. Ron swore, Flitwick said something too quietly to catch, and then the rope eased with one steady pull towards the surface.
They climbed into the upper passage to find Ron kneeling beside the channel with a spare wooden block under his palm. The large slab hung half lowered, caught on the block instead of sitting in its slot.
"It tried to go down on its own," Ron said. "Thought that was a bit eager."
Dumbledore helped Percy clear the last step. McGonagall counted them with her eyes before looking at the slab, and Percy found he was absurdly grateful to be a number somebody was checking.
Hermione explained the linked stone tongue while Flitwick secured the upper slab with a second block. Ron stared at the card beside his knee, then turned it face down.
"Right. New instructions."
Nobody argued with him. Percy sat on a storage crate and waited for his hands to stop shaking before anyone could mistake them for confidence.
----------------------
They closed the channel only after Flitwick had confirmed the lower tongue moved with it. He used a plain length of wire and a mirror to watch the linkage, refusing Hermione's offer to go back down with such cheerful finality that even she couldn't find an opening.
Once the stone settled, the air in the passage warmed. Percy hadn't noticed how cold it had become until his fingers began to sting around the handle of the lamp.
Dumbledore asked about the water in the hollow. Percy described the two beads, the interrupted image, and the distant feeling of a clamp being tightened, but when he reached the kitchen he stopped.
Harry was watching him without curiosity. That made it possible to say the next part without turning it into a joke.
"It used somewhere I remember. Somewhere I couldn't get back to by walking."
Dumbledore nodded once. He didn't ask who had been standing by the sink, and Percy decided to be grateful before suspicion could ruin it.
"Then proximity gives it more material," Hermione said. She looked ill at the thought. "Or the chamber does. We shouldn't assume it knew everything before we arrived."
"And it used what it had immediately," Harry said. "It didn't wait for Percy to touch anything."
Ron rubbed the edge of his ruined instructions with his thumb. "It also tried to shut the way out while you were still looking around. That's a fairly strong opinion about visitors leaving."
McGonagall sent him upstairs for water and something to eat. He refused until Flitwick took his place beside the blocked channel, and the professor accepted the handover with the seriousness of a guard relieving another guard.
Percy watched the exchange. Yesterday the fourth place had sounded like an unfair consolation prize, but Ron had just kept three people from being trapped without casting a single spell.
Hermione spread a drawing of the grooves on a crate. She left the actual language off it, using plain circles and arrows while Harry corrected the position of the little stone tongue.
"The return joins outside the agreement," she said. "Which means we don't need to hold all three parts together while we're inside it. We need to get them through the threshold."
"Need," Snape said from the doorway, "is doing a great deal of work in that sentence."
He had arrived quietly enough to make Percy wonder whether the man practised. Harry straightened, but when Snape asked about his scar he answered with facts rather than taking the question as an accusation.
The cold had sharpened in the chamber. The foreign relief hadn't become Harry's own, and he'd managed to recognise the difference while watching Percy instead of concentrating on himself.
Snape listened without praise. Then he told Harry to write down exactly what he had been attending to, which from him was practically a commemorative plaque.
Dumbledore studied the empty sea hollow on Hermione's sketch. Percy followed his gaze and understood the problem before the headmaster said it aloud.
"We made no offering," Dumbledore said. "Yet something arrived."
Percy could still feel the clamp in the memory of his nerves. Voldemort wasn't merely standing somewhere far away with a bottle of dangerous water; the stolen sample had already found a place in the mechanism beneath their feet.
Hermione drew a second arrow leading into the sea hollow. She hesitated before putting its origin beyond the edge of the page.
"Then there are two people trying to use the same place."
"One person," Percy said. He stood carefully, because his knees had opinions about the morning. "And one thief with maintenance problems."
Under the castle, something knocked once against the closed channel. The sound was small enough to ignore if they hadn't all been listening, and none of them pretended they hadn't heard it.
===========================
OOH RAHHH
RHGHUSIHUIBCOS
ITS ACTUALLY 5 AM RIGHT NOW OMFG
But it's okay.
This is for you guys.
And now,
I don't have to write any more chapters until I run out of this stockpile (next week prob)
K BAIIII! :3
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