Kevin's first thought was the alchemist.
His second was a quick look at Dumbledore, whose expression communicated that yes, this was the real Nicolas Flamel, and yes, he had known the letter was coming, and yes, Kevin could ask about that later.
He broke the seal.
The letter floated free of the envelope — not unusual, he'd seen enchanted correspondence before — but what followed it was unexpected: a tiny ruby, no larger than a pea, which blazed briefly and intensely bright before settling to a steady warm light.
Kevin's bracelet lit up. He felt it before he saw it.
Hermione's wrist, beside him, did the same.
They looked at each other.
The ruby blazed again. The air above it shifted — and resolved, slowly, into the figure of a very old man. White-haired and slight and bright-eyed, his hologram flickering slightly at the edges with the imperfection of a long-distance projection. He looked around the room and appeared pleasantly surprised by the number of people in it.
"Oh! Hello, everyone." A small, cheerful wave. He located Dumbledore and his expression warmed further. "Albus. It's been entirely too long."
"Nicolas," Dumbledore said, with genuine warmth. "Thank you for coming."
He introduced the room. Flamel took it in with the patience of someone who has been watching young people discover things for nearly seven hundred years.
"You're Kevin," he said, pointing at the bracelet.
"Yes. Should I call you —"
"Nico," Flamel said. "Or Grandpa Nico, if that feels right. I'm open to it."
Kevin, who was seventeen and had just killed Voldemort, said, "Grandpa Nico, then."
Flamel beamed.
He asked to see the bracelets. Kevin held his wrist out. Then Hermione stepped forward beside him and did the same — both of them side by side, both bracelets still faintly lit.
Flamel's eyes moved between them. He set down the book he'd been carrying, flipped it open on the holographic desk that apparently existed wherever he was calling from, and said:
"I'm going to tell you what these things actually are. And I want to be clear before I start — some of what I'm about to say is not good. But it's fixable. Don't panic until I finish."
Hermione's grip on Kevin's hand tightened very slightly.
"You've heard the two basic functions. Worn alone, it nourishes the soul. Worn as a pair, the wearers' souls partially merge and the bracelet acts as a Horcrux-analogue — if one dies, the other can follow the soul's thread and bring them back." Flamel paused. "Both of those things are true. But here's the question no one's ever thought to ask."
He looked at Kevin directly.
"Where does the nourishment come from? What's feeding your soul every time you wear this thing?"
The room was quiet.
"Souls don't draw on ambient magic. They don't run on alchemy. They can only be sustained by other souls."
He let that sit for a moment.
"The Chain of the Spirit Ruins — that's its real name, not what you've been calling it — was built by a student of mine. A very talented one, born with a soul that had been damaged before his first breath. The damage gave him extraordinary ability and cost him everything that might have made him use it wisely." Flamel's voice had gone quieter. "He built this to solve his problem. A device that collects souls, strips away the conscious layer, and converts the remaining energy to fuel."
Another pause.
"Anyone who wears it and activates its function gets marked by the magic. When they die, their soul is drawn in automatically. No exceptions. No override." He looked at the bracelets. "That includes, eventually, the people who are wearing them right now."