Katherine and Thomas found themselves in a chamber hung with mirrors, every surface throwing back some version of the two of them that did not quite match what either of them remembered themselves looking like, and had perhaps a full minute to take in the strangeness of it before a voice reached them from somewhere among the reflections.
Katherine had never liked mirrors much, even before this one. She had spent enough of her childhood catching her mother's face doing the specific tight, worried thing it did whenever Katherine's dark element flickered too visibly close to the surface, and mirrors, ever since, had felt less like ordinary furniture and more like a kind of test she hadn't asked to take. This chamber multiplied that unease a hundredfold. Every surface seemed to be sampling outcomes, trying on futures the way a person tries on coats before choosing one to actually wear out the door.
"You must be the dark element," the voice said, warm and rich and entirely too pleasant for the chamber it belonged to. "I've heard so much about you. I imagine everyone who's ever met you has told you exactly what they think you're capable of."
Sabrina Luxuria stepped out from between two mirrors as though she had simply been standing behind glass the entire time, dark hair loose, the designed and terrible beauty the tube had preserved catching the chamber's strange light from every angle at once.
"Seventh of seven," she said. "Though I suspect you already worked that out."
"We did," Thomas said. "Katherine, don't listen to anything she says next."
"I wasn't planning to say anything to her," Sabrina said, and there was something almost hurt in it, a performance so smooth Thomas felt it land somewhere in his own chest despite every warning he'd given himself walking in. "I was going to talk to you, Thomas. You're the interesting one, aren't you? The man who spent eleven days working up the courage to propose to a woman who is, by all accounts, about to become something considerably larger than either of you." Her voice dropped, warm and confiding, the specific total attention that had once ruined two houses and quietly ended a third. "Doesn't that frighten you. Being the ordinary one in a story about to belong entirely to her."
"You don't know anything about us," Katherine said, stepping half in front of him without quite meaning to, the dark element already stirring restless under her skin.
"I know everything about wanting," Sabrina said, unbothered, her eyes never leaving Thomas. "That's the whole of what I am. And I know a man who measures his own worth against a woman's power when he thinks no one is watching him do it. I've met a thousand men like you, across three hundred years and a great many courts. It never once ends well for the ones who let the measuring win."
It cost him a half-second — a half-second of genuine, unbidden doubt, the particular ache of a man who had spent two years watching KaSandra become steadily more extraordinary while measuring his own worth against formations and drills and the specific unglamorous competence of keeping people alive — and in that half-second Sabrina moved, fast and silent, closing the distance toward him with an expression of total, devastating sympathy on her face.
"Thomas," Katherine said, sharp, "she's not talking to comfort you. Look at what she's doing while she talks."
The words cut through the doubt just enough. Thomas's training reasserted itself the way training was built to, faster than feeling, and he threw himself sideways as Sabrina's hand closed on empty air where his shoulder had been a half-second before.
She recovered with a speed that surprised even him, spinning to face them both, and for a moment her carefully warm expression flickered into something colder, more calculating — the specific look of a predator recalculating a strategy that had just failed to land.
"You're faster than most," she said, almost admiring. "But speed isn't the same as certainty, Thomas. I only need you to doubt yourself once more. A single moment is usually all it ever takes."
"Try it," Katherine said, and let the dark element rise fully now, no longer restless but present, coiled and waiting.
Sabrina's eyes flicked to her, assessing, and something in her expression shifted toward genuine curiosity. "You're not afraid of me," she said. "That's unusual. Most people are, once they understand what I can show them about themselves."
"I've already seen the worst thing about myself," Katherine said. "I carry it under my own skin. You don't have anything left to show me that I haven't already made peace with."
Katherine's dark element caught her a moment later, when Sabrina lunged again, this time for Katherine directly, perhaps sensing that Thomas's guard had steadied too much to be worth a second attempt.
It moved through the mirrored chamber like ink through water, formless and total, and Sabrina's charm — built entirely on being perceived, on the specific total attention she demanded from every eye in a room — found nothing to work with in an element that did not perceive the way ordinary sight perceived, that simply reached and took without ever once needing to be persuaded of anything.
"That's the thing about darkness," Katherine said, calm in a way that surprised even herself, "it doesn't need to believe you to hurt you."
Sabrina's warm, rich voice cracked for the first time, genuine fear breaking through three hundred years of practiced charm as the dark element wrapped around her, and in the mirrored chamber a hundred reflected versions of the same moment played out at once, Sabrina Luxuria's careful beautiful mask finally, entirely, dropping.
"Wait," she said, and for one strange instant it sounded almost like the woman from the garden, three hundred years and a lifetime ago, the one who had left without answering a man who saw her clearly. "I never wanted—"
The dark element did not wait.
When it finished, the mirrors held nothing but Katherine and Thomas, breathing hard in a chamber suddenly, entirely silent, every reflected surface showing only the two of them, unmultiplied, ordinary, alive.
"Are you all right," Thomas said, reaching for Katherine's shoulder with a hand that was not quite steady.
"I will be," Katherine said. "Are you?"
Thomas thought of the half-second Sabrina's words had found purchase in, the specific shape of the doubt she'd aimed at him with such practiced precision, and understood that naming it honestly mattered more, in this moment, than pretending it hadn't landed at all.
"She wasn't entirely wrong," he admitted. "I have wondered it. Whether I'll still fit beside KaSandra once she's finished becoming whatever she's becoming."
"And?" Katherine said.
"And I don't think that's a question a demon gets to answer for me," Thomas said. "I think it's one I get to keep asking honestly, for as long as it takes, without letting anyone weaponize the asking against me." He looked around the chamber, at the mirrors finally showing only what was actually there instead of a hundred manufactured wants. "Ask me again after this is over."
Katherine studied him for a moment, and something in her expression softened. "For what it's worth," she said, "I don't think KaSandra becoming something larger has anything to do with whether you fit beside her. I've watched the two of you for two years. Whatever she's carrying now, it doesn't change what you two actually are to each other. It just means she's carrying more."
"When did you get so wise about this," Thomas said, managing something close to a smile despite the chamber's lingering strangeness.
"I've had a very long two years of watching people I love almost lose each other to things exactly like that room," Katherine said. "I've learned a few things along the way, whether I wanted to or not."
Thomas leaned back against one of the now-still mirrors, catching his breath properly for the first time since Sabrina had first spoken. "I keep thinking about what she said, though. Not the manipulation — I understand that part, I understand exactly what she was trying to do. I mean the specific shape of the doubt. She didn't invent it out of nothing. She found something that was already there and simply amplified it. That's what unsettles me. Not that a demon can lie convincingly. That she could find a true thing to lie with."
"Every general we've fought seems to work that way," Katherine said, considering it. "Erin found real hunger. Amelia found real unfairness. I'd guess it's the whole design of what they are — the demon queen didn't build monsters out of nothing. She built them out of real human wounds, sharpened into weapons. That's what makes them so dangerous. And it's probably also what makes them beatable, if you know to look for the true thing underneath the weapon instead of just the weapon itself."
"That's a colder way of thinking about it than I expected from you," Thomas said.
"I've had a colder two years than either of us expected," Katherine said, not unkindly. "Come on. The others need us, and I don't like leaving the room where Kristen's still — where she's still out there somewhere in this castle, unaccounted for. I'd rather be moving than standing still with that thought."
They found their way back into the corridor together, and neither of them looked back at the mirrors, which had nothing left in them worth looking at.