The Mirror World didn't survive Grindelwald's absence long.
Without his magic maintaining the boundary, it folded — not dramatically, not with a bang, but with the quiet exhaustion of a thing that has been sustained by will rather than nature. The frozen rain finished falling in the space of two seconds. The suspension of the park returned to ordinary London stone and grass, the stone platform smoothing back to nothing, the air rushing back in.
They were standing in Central London in the rain again.
The Death Eaters Kevin had frozen during the assembly were still frozen, lying scattered across the wet grass. The ones who'd managed to Disapparate were gone, which was a problem for another day. Hermione and the others were already coming through the park entrance at a run, Aurors moving in behind them.
"Kevin." Hermione reached him first. She looked at the ruins of his cloak and made the expression she made when something she cared about had been damaged but there were more urgent matters at hand. "Are you hurt?"
"Fine." He held up his hands. "All intact."
"The Grindelwald here," he said to the Aurors, who had arrived and were fanning out across the unconscious figures, "was a mud clone. The real one wasn't present." He gestured at the collapsed pile of clay and material near the platform's former location. "That's what's left of it."
The lead Auror, a solid woman with close-cropped hair who had clearly been briefed on Kevin before this morning, did not visibly react to the information that a mud clone of Gellert Grindelwald had been deployed in Central London. She filed it the way professionals file things that are significantly stranger than their standard working day.
"Mr. Croft. Thank you for holding the assembly in place until we arrived."
"Most of them bolted anyway," Kevin admitted. "The ones on the grass are all yours."
The Auror looked over the unconscious figures. "You mentioned this isn't your first encounter with Grindelwald."
"Second. The first was Malfoy Manor."
"Why wasn't the Ministry notified at the time?"
Kevin looked at her. "Because I didn't know his name. I found that out today."
"..."
There was a brief pause during which the Auror visibly adjusted her mental model of the situation.
"Understood. Mr. Dumbledore is aware?"
"Has been since the Manor. He's been looking into it." Kevin paused. Then: "Apparently there's some history there."
The Auror nodded slowly. That, at least, was a piece of context she had already been working with.
The Death Eaters were gathered and removed. The park returned to ordinary London normalcy with the brisk efficiency of wizards who had been doing this a long time. Within twenty minutes, the only evidence anything had happened was a series of slightly flattened patches on the grass.
Kevin's group regrouped by the park entrance.
"Right," Harry said. He was looking at Kevin with the slightly stunned expression he'd worn since the mud clone had stopped fighting. "So... what do we do now?"
"I invited Draco back to the barbecue," Kevin said. He slung his arm around Draco's shoulder. Draco, who had been standing to one side with the slightly disoriented look of someone whose very large secret had just become significantly larger, didn't resist. "We're going home."
"Home," Harry repeated. He looked at Ron. Ron looked at him.
"...The barbecue," Ron said, slowly.
"The barbecue is still happening," Kevin confirmed. "Lupin's still there. The food hasn't gone anywhere."
He started walking. After a moment, everyone followed.
Somewhere in an empty manor on the German border, Dumbledore materialised in the garden without a sound.
Grindelwald was already there, standing at a low window, watching the rain on the glass. He turned when Dumbledore appeared, and smiled — the warm smile, the one he kept for very few people.
"You didn't come to London," Grindelwald said.
"I could see perfectly well from here what was happening."
Grindelwald laughed quietly. "Your student is something, Albus. He broke my clone's armour charm in under a minute. Through the head, no less. I don't think I've ever been decapitated before. It was rather novel."
"And the speech?" Dumbledore asked.
"Delivered. The seeds are planted. Voldemort's base is fracturing considerably faster than he expected — I've disrupted the fear that holds them to him." Grindelwald paused. "Also, your boy went immediately for the throat on the 'new ideas' problem. Traced the long-game strategy back to its actual goal within minutes of hearing it."
Dumbledore was quiet for a moment.
"The letter," he said. From his inner pocket, folded precisely, came the note Kevin had sent weeks ago. The one with the analysis. The one that had, if Dumbledore was being honest with himself, stopped him from making at least two significant errors of judgement. "I know."
"How long are you planning to keep them in the dark?" Grindelwald asked. "About me. About us. Our history."
Dumbledore unfolded the letter slowly. Looked at Kevin's handwriting — blocky, practical, entirely unaware of how much it had already told him about the boy who'd written it.
"They know you exist now. They'll want the context next."
"Then give them the context."
"They're rather good, Gellert," Dumbledore said mildly, pocketing the letter.
Grindelwald looked at him with an expression that was, for the first time in the conversation, something approaching genuine warmth.
"Yes," he said. "They are."
The rain continued outside, steady and unhurried, as the two old men sat together in the empty manor and let the silence settle around them like an old coat.
This story don't stop here, y'all. It never did, not once. More chapters breathing and waiting right beyond this page like a river that just keeps on running. Don't you leave curiosity unanswered, folks. That ain't right.