The common room celebration had reached the specific density of a party that had found its own momentum and no longer required anyone to maintain it, which was the correct state for a party to be in.
Harry was at the centre of it, which was where Harry always was when something had gone well — not by choice but by the specific gravitational quality of someone who had done the thing everyone was celebrating. He was managing it with the ease he had developed across third year, receiving the congratulations without deflecting and without performing, which was the hard middle path between two bad options and which he had learned to walk.
Ron was on the hearthrug with the golden egg.
Harry had handed it to him twenty minutes into the party with the specific quality of someone who had been carrying something for several hours and had decided that the person most likely to do something useful with it should have it. 'You should open it,' Harry had said. 'You'll know what to do with what's inside.'
He turned it over in his hands. It was heavier than it looked, the gold warm from Harry's carrying it, the surface decorated with a pattern of scales that caught the firelight. The seam ran around the equator — a hinge, a latch, the specific design of something that opened.
He looked around the room. The party was loud. The sound would be considerable.
He found Hermione's eyes across the room. She was already watching him — she had been watching him since he sat down with the egg, with the quality of someone who had noted that Ron had the egg and was waiting to see what he did with it. He tilted his head fractionally. She crossed the room.
'Wand out,' he said quietly, when she was beside him.
'Why —'
He opened the egg.
The sound that came out was — not pleasant. It filled the room with the specific quality of something that was not designed for air, a shrieking wail that cut through the party noise and produced, across the Gryffindor common room, the collective expression of people encountering something they had not prepared for and were not enjoying.
Ron closed it.
He had already cast — a Sound Barrier, circular, covering himself and Hermione and Harry who had come over immediately, drawn by the sound. The barrier went up in the same moment as the egg closed, silent from inside once the egg was shut.
Around them the common room was recovering — Fred with a hand over one ear, Ginny looking at Ron with the expression of someone who had decided he had done that on purpose, which was not entirely unfair.
Inside the barrier it was quiet.
'Open it again,' he said to Harry.
Harry opened the egg inside the barrier. The sound came again — the same wail, contained now, and inside the containment it was possible to listen to it rather than simply experience it. He listened with the attention of someone who had been thinking about this problem since June.
It was not a wail. It was a voice. Several voices, overlapping, singing in the specific tonal pattern of a language he recognized.
'Mermish,' he said.
Hermione looked at him. 'You can identify Mermish on first hearing?'
'I've been studying Gobbledegook,' he said. 'The tonal structure is similar enough. Different language, same underlying grammar of how magical creatures encode meaning in pitch.' He looked at Harry. 'The clue is in the water. Mermish is their language — it only sounds like screaming in air. Submerge the egg and you'll hear what it's actually saying.'
Harry looked at the egg. Then at Ron. 'How do you know that?'
'The same way I know most things,' Ron said. 'I read it, and then I thought about it, and then I kept thinking about it until it made sense.' He paused. 'You'll need a basin large enough to get your head in. Clean water, still.'
He turned to the room. The Sound Barrier extended to perhaps four feet around the three of them. Outside it, the common room had resumed its party — slightly more cautiously, with people giving the golden egg a wider berth than before. Several sixth and seventh years were watching them with the quality of people who had noticed something and were still processing what they'd noticed.
He had not thought about the audience for the next part.
He pointed at the floor.
The Conjuration came without effort — a large basin, ceramic, water-filled, appearing on the common room floor with the specific clean quality of magic that had been performed so many times in practice that the performance had ceased to require thought. It was large enough to accommodate Harry's head and shoulders with room to spare.
The silence in the common room had a different quality now.
He became aware that the party had largely stopped.
He did not look up from the basin. He checked the water — still, clean, the temperature correct — and straightened.
'Egg in, head in,' he said to Harry. 'Listen for words rather than sound.'
Harry got down beside the basin with the practical willingness of someone who had spent three weeks doing things that looked strange in service of things that worked. He placed the egg in the water and submerged his head alongside it.
The common room was very quiet.
After a minute Harry came up.
He had the expression he had when he had received something important and was still in the process of receiving it. 'They've taken something,' he said. 'An hour to find it or lose it forever. In the lake.'
'Yes,' Ron said. 'Second task.'
'You already knew.'
'I knew it was Mermish. The content is yours.'
Harry looked at him. Then he nodded, in the way he nodded when he had decided to accept something and was satisfied with the accepting.
Someone in the common room started clapping.
It began with the sixth-years — the two who had watched the Conjuration with the quality of students encountering the work of someone who should not, by the logic of the curriculum, be able to do what they had just watched him do. Then it spread, with the specific momentum of people who had been watching something they didn't fully understand and had decided that understanding it fully was less important than acknowledging that they had seen it.
He released the Sound Barrier. The applause filled the room.
He picked up the basin and handed it to a first year to return to wherever it came from and went back to the hearthrug.