They stayed three more days.
Wren insisted on it, over KaSandra's objections and Thomas's louder ones, and Sister Perpetua's quiet unmoving agreement settled the argument in the way Sister Perpetua's agreement settled most arguments in the coven, simply by being present and unhurried until the other side of the argument ran out of energy to keep pushing against it. Thomas needed the days. Whatever the gold-white light and KaSandra's own reluctant honesty had pulled out of him, it had not left him unmarked — he tired faster than he wanted to admit, and slept longer than his own stubbornness was comfortable with, and KaSandra found herself, more than once, simply sitting beside him while he slept, watching the evenness of his breathing with an attention that had nothing left to fear in it and everything left to be grateful for.
It was on the second of those three days that Sister Perpetua found her alone in the healing hall, Thomas resting nearby, and asked her to walk.
"Not to the inner chamber," the old woman said, before KaSandra could ask. "You've done what that room needed of you. This is a different walk, and a different room, and I think you are finally ready for both, though I do not think you will believe me when I say so."
They went higher than KaSandra had ever gone — past the First Voice's chamber, past even the final stair she'd climbed two days before, up a narrow path cut into the mountain's own bones that seemed, the higher it climbed, to grow less like stone and more like something else entirely, something that hummed faintly under her feet the way the inner chamber's thread had hummed under her skin.
"What is this place," KaSandra asked.
"The oldest room the coven has," Sister Perpetua said. "Older than the coven itself, if the old texts are to be believed, which I have found, over several centuries of reading them, they generally are. It predates even the First Voice's title. It is the room your grandmother came to, once, though she never told you that, and her grandmother before her, and so on back further than any record this mountain keeps has bothered trying to count."
The path opened onto a chamber unlike anything KaSandra had seen in this coven or anywhere else — round, open entirely to the sky rather than merely apertured toward it, the mountain simply ending around them in a bowl of ancient worn stone that seemed to hold the whole turning sky within its rim. The wrong bright stars she'd seen through the inner chamber's aperture were fuller here, denser, arranged in patterns that made something in KaSandra's chest ache with a recognition she had no memory to attach to.
"I know this place," she said, quietly, surprising herself with the certainty of it.
"You shouldn't," Sister Perpetua said. "You've never once been here in this life. But I am not surprised you recognize it, KaSandra Lucas, because the recognition is not memory. It is inheritance."
"I don't understand."
"You will." Sister Perpetua walked to the chamber's center, where a single dark stone stood embedded in the floor, worn smooth by a use so old the wearing itself had become a kind of history. "Your grandmother never told you what she was, because she believed the telling would make you a target before you were old enough to defend the knowledge, and she was not wrong to fear that — it very nearly made you a target regardless, three hundred years ago, when the trade you and Patricia both made was struck in exactly the shadow of what I am about to tell you. But you are not nineteen anymore. You are not unprotected. And the world you are about to walk back into, with a demon queen loose and seven generals waking and a woman named Mireille Voss building whatever she has spent three centuries building in the dark, cannot afford you continuing to walk through it only half-armed."
"Half-armed," KaSandra repeated.
"The thread you touched two nights ago," Sister Perpetua said. "The cosmic power your family has carried, quietly, for longer than the coven has kept records — you have always believed it was simply a gift. A particularly strong one, inherited the way a strong gift is inherited, notable but not extraordinary in kind, only in degree." She turned to face KaSandra fully, and something in the old woman's ancient, unhurried face had gone, for the first time since KaSandra had known her, genuinely solemn. "It is not that kind of gift. What runs in your bloodline, KaSandra — what your grandmother carried, and her grandmother before her, each of them passing down a portion of it too dangerous to give whole to any single generation — is not a strong version of ordinary magic. It is the seed of something the old texts call, without much poetry about it, the next carrying. The inheritance of the world's balance itself, waiting for the generation strong enough, and honest enough, to hold the whole of it at once instead of only the fragment each of your ancestors was trusted with."
KaSandra felt the stone chamber tilt slightly beneath her, though nothing had physically moved.
"Say it plainly," she said. "I have had enough of this mountain's fondness for saying enormous things carefully. Say it plainly."
Sister Perpetua held her gaze without flinching.
"You are becoming what this world calls a goddess," she said. "Not metaphorically. Not as an honorific. The cosmic thread your family has carried in fragments for generations has been waiting, all this time, for a single carrier capable of holding the whole of it without breaking under the weight — and two nights ago, in the inner chamber, when you finally opened the door you'd spent years bricking shut, you proved yourself exactly that carrier. The thread did not simply heal Thomas, KaSandra. It recognized you. It has been settling into you, fully, every hour since, and by the time you leave this mountain you will not be the same woman who arrived on it four days ago carrying a dying man and a lifetime of unspoken hatred."
For a long moment KaSandra said nothing at all.
"Why me," she said finally. "Why now. My grandmother carried a fragment of this her whole life and never once became what you're describing. Why does it choose me, in the middle of the worst war this world has fought in three hundred years, instead of settling quietly the way it settled in every generation before mine?"
"Because every generation before yours was not asked to open the door you opened two nights ago," Sister Perpetua said. "The thread does not choose based on bloodline alone, though bloodline is the door it can knock on. It chooses based on the specific, terrible honesty of a person willing to look directly at the ugliest thing inside themselves rather than around it, in a moment when looking costs them everything they have left. Your grandmother never faced a door like that. Neither did her grandmother. You did, in that chamber, for a man you love enough to risk it, and the thread answered you the way it has apparently been waiting three generations to answer someone." The old woman's voice softened, just slightly, the closest thing to gentleness KaSandra had heard from her since the gate. "I do not think this will feel like a gift for some time yet, KaSandra. I think it will feel, for a while, like an enormous and frightening weight settling into a body that was not built with any warning it was coming. But I have watched this mountain and this world for a very long time, and I do not believe the thread makes mistakes about who it chooses to carry it."
KaSandra looked up at the dense, ancient stars filling the chamber's open bowl, and thought of Thomas resting three days below her in the healing hall, and of Patricia three hundred years silent at the top of a stair KaSandra had only just learned to climb, and of a house full of people waiting well because waiting well was the only thing left they could offer.
"Then I suppose," she said, quietly, "I had better learn what carrying it actually means, before I take it back down that mountain into the middle of a war it apparently exists to help end."
Sister Perpetua, for the first time since KaSandra had known her, allowed herself something that was almost a smile.
"That," she said, "is precisely the correct place to begin."