A whoosh and the rustle of satin curtains in the Alpine breeze, and he stands by the window, adjusting his coat and looking around the room.

Sumptuous décor, as expected, though not as grand as the library, with its acres of shelves and windows spanning the height and breadth of the castle. Silk and velvet, marble floors shimmering obsidian. Dark green pillows and deep charcoal throw on the four-poster bed. The heavy curtains swallow noise, streaming down from a dark panel disappearing in the sprawling gloom.

Gellert stands with the back to him, shoulders rigid in an emerald waistcoat. He's not turning around, not looking up. The right side of his face reflects in the gilded mirror of the dressing table. The quirk of his mouth is the same, the crowfeet feathering cheek and temple are new. Albus can't look away from the eyelashes brushing the delicate skin around his eyes. So pale, they're nearly transparent.

"You got my invitation." Gellert's voice is calm, low like it always used to be. A voice that makes you want to be still and listen.

Albus's throat constricts. "I had to see for myself," he admits. His voice is level, light. Unconcerned to his own ears.

Gellert shifts. Can he hear the tension vibrating just under the surface? "You've disarmed the anti-apparition spell." Albus glances through the window behind him. Storm clouds in the dusk, dramatic mountain scenery looking like a washed-out photograph. "You're braver than I ever was."

Gellert shrugs. "Just for this room." He undoes the Ascot knot. "It's worth the risk." The tie slides from his shirt collar with a soft hiss. "To see you, I'd take much bigger ones."

He looks up, and Albus's breath hitches.

One eye only is visible in the mirror, the silver one. The iris constricts, and Albus's heart jumps in his chest. Gellert turns around.

He's older, tired. Face lined, his fair colouring making him look translucent. They've aged, but have they changed? Albus's hair is turning grey, he feels that same fatigue he can see in his old school friend.

So much more than a brother. His lover, the only man who's ever won his heart. Won it, and destroyed it.

Gellert is moving. He comes towards Albus, strides lengthening, and if the room were any bigger he'd be running. And when he reaches the window, he throws his arms around Albus, bruising him in that same exuberant embrace as always, the one Albus won't forget until the day he dies.

Their eyes lock, just for a moment, and Albus feels the ground give way under his feet, or he thinks he does. He falls, head over heels, his stomach turning somersaults as the years rush by, fall away, and they're seventeen again, flush with the unexpected joys of first love.

And their lips meet, in a crush of emotion and hunger, and the blood roars in Albus's ears with the anticipation of Gellert's desire.

A spell could take care of their clothes all at once, but Gellert opts for lightning-fast fingers, popping buttons, ghosting under shirts. Groins press close and to Albus, the last thirty years are nothing but a bad dream.

Was this why he came here?

Yes. He has to be honest with himself. This, and the hope to stop what can no longer be stopped.

Maybe it could never have been halted, not by him or anyone. Maybe this is how it had to be.

What comes next is familiar too, Gellert taking charge, tugging him towards the four-poster, pushing him down into the sumptuous sheets. His eyes are everywhere but on Albus's face. He trails fingers over a body unfamiliar, yet previously as well-known as his own.

"Why did you invite me here?" Albus pants.

Gellert places kisses along his collarbones. "Why did you come?"

"I didn't bring it." The words are out before Albus can stop them. The pendant is safe, and the memory of its location stored in the Pensieve in his office. Newt has told him about Queenie's mind-reading abilities.

"I didn't think you would." Gellert's breath is hot against Albus's belly, holding still for a moment.

Albus glances down. "So what is this? A trip down memory lane?"

Gellert looks up, raising a fragile, pale eyebrow but doesn't speak. Albus drops his head in the pillows.

Maybe it is.

The thing itself is breath-taking, and over much too soon. Albus marvels at the sounds Gellert makes, at how he trembles and writhes beneath him. It's just as he remembers from their stolen hours in the astronomy tower, or hidden away in the broom shed late at night. Stretched out on the pearly-grey satin sheets, Gellert looks and feels and tastes the same as he did sprawled on both their cloaks for warmth on the dusty floor under the stars, legs in the air, gripping fistfuls of fabric as the throes of climax take hold.

Afterwards, it's different. They're on borrowed time, stolen minutes. They lie tangled in each other, Gellert's pale head resting on Albus's chest, his warm flank pressed into his side, their hearts beating together. Yet he's not really there. Albus can barely feel the weight of him, like Gellert is nothing but a ghost, is already up and away to wherever his nightmare future will take him.

At seventeen, a night was a lifetime. At fifty, decades slip by in the blink of an eye.

"Don't do it, Gellert," Albus whispers into the dark. "It's not too late to stop it all."

No sound but Gellert's breathing, his fingers trailing shadows on Albus's chest. "Stay here," he whispers back. "Stay here, and we do it together. I want peace. With you involved, my world will be better for everyone."

Albus says nothing. There is nothing to say, no argument to be made. The dice are cast.

He disentangles himself without hurry, without heat. One flick of his wand, and he's clean and dressed. He tugs his coat collar straight, steps close to the window.

"Goodbye, Albus." Gellert's voice echoes in his heart as Albus raises the wand and the room dissolves.