The tower was cold, it was always cold but he had long grown used to it. School had often been cold, with fires only lit for educational purposes. There had been warmth then though, a warmth found in companionship and friendship. Then the cold had spread, leeching through his skin and chilling his heart, freezing it in his chest and hardening it to the world. Deep within, a new fire had kindled, this one cruel and angry, raging and searing against those who had wronged him. It burned, kept him alive despite his frozen heart.
And he had relished it. He'd wrapped that fire around him and let it burn the world even whilst it sustained him. He'd vowed to never let the coldness touch him again.
He was old now, his skin haggard and his teeth rotten. His once fine clothes hung in tatters over gaunt shoulders that curled over like a fish hook, only matched by the ragged talons of his fingers. His bones stuck out like the knuckles of the elder wand that had once been his and his chest wheezed with every breath. Yet, like she had, he rose every morning to watch the morning out of the window, creaking open the rusted hinges and allowed frigid air to blast bedraggles locks away from his crinkled eyes. He basked in the heat of the rising sun, like he'd once basked in the hot fire of her magic.
He was like an addict to a drug that had long been removed from his grasp. He reached for the mere memory of her, yet found nothing that could ever come close to filling the void that her departure had left, deep beneath the cold and the anger.
The dark, icy behemoth of his magic stirred, like it had done every day for half a century, spilling from his fingers and flooding out across the land. It wove it's way through the air, saturating it with his power and influence. He pushed it further and further until he felt hollow, except for the heat of the sun upon his skin.
A pale imitation.
With a savage twist, he tore at the fabric of the sky. His magic coiled and spun, whipping dark clouds across the sun and extinguishing it's light, plunging the dark tower into the perpetual darkness that it lived in. Rain lashed the stone facade, spraying against his skin as thunder boomed at the rough change he'd forced upon the elements.
A spark of life ignited against his consciousness. It flickered against the distressed sky, drawing his attention. Surprised and curious, the prisoner reached out to it. It was racing towards him, flying even as the magical storm battered at it.
He reached out again, stilling the air and easing the passage of his visitor. In the physical plane, a large, tawny owl passed through ancient wards. A seal flared brightly on the letter it carried, allowing it access to the heavily secured prison. Mismatched eyes followed it's course as it fluttered down and a moment later the prisoner stumbled backwards as the bird alighted on his windowsill.
He knew exactly whom had sent the letter; the man who had stolen everything he had left, the imposter who had once called himself his brother. The one who had stolen his seal and his castle, twisting and modifying wards that she had designed for him.
A skeletal hand jerked out, snatching the letter with a vicious fury that almost tore the cheap parchment his foe had always written upon. He cracked the seal, allowing the almost sacrilegious purple wax it had been pressed into fall in flakes to the ground. He hated that the man had written to him now after so long, yet at the same time his insatiable curiosity stirred, wondering what need his foe had of him now.
The missive was short, splattered with ink where the quill had snapped with the anger of the writer. The writing was even messier than the usual scrawl of the ill-educated, jagged with haste and emotion.
"Who is Hermione Granger of Gorlois?"
The prisoner read it once, then two more times, barely believing the words he was reading. Then he looked at it again, noting the exact words that had been used. Never once had he used her muggle name since she had left, there was no reason for his enemy to know it. There was no way he could know it, she had gone by Gorlois at school and most people in their childhood had known her simply as the Grindelwald ward.. Unless... unless she'd told him herself. He'd used the present tense, rather than the past...
An idea occurred to him, one so outlandish and wild that he could barely believe it. Except, the more he thought about it, the more things seemed to slide into place. Strange occurrences and reactions, things that hadn't quite added up but he'd glossed over at the reassurance of his mother.
In a dark, bleak tower high in the windswept mountains, miles from the nearest settlement, Gellert Grindelwald laughed.