She dropped onto his roof the following morning like she'd jumped from the next building over, which she had, and pointed a crackling arc of lightning directly at his face before he could reach his workbench.
"Where is it?" she said.
Kael raised his hands. He had the pulse-glove on his right hand, but she'd gotten the jump on him and he was fairly sure discharging it into a live lightning bolt would end badly. "Where is what?"
"The energy signature from three nights ago. The Architect resonance. I tracked it to this building, this floor, and —" she stopped. She was looking at the Nexus Core on the table. Her eyes changed. Something flickered through them — recognition, but deeper than recognition. Something that went all the way down. "That's it," she whispered.
The lightning around her hand faded without her consciously dismissing it. She took a step toward the table.
Kael stepped between her and it.
She looked at him like she'd momentarily forgotten there was a person in the room. She was about his age — sharp dark eyes under a mess of silver-streaked black hair, dressed in a storm-grey traveling coat still damp at the edges, a mage's inscription ring on her right thumb. She looked like someone who hadn't slept in two days and had strong opinions about this.
"That's my property," Kael said.
"It's no one's property," she said. "It's a fragment of the Nexus Core. Do you even know what you have?"
"Funny you should ask that," Omen said from the table.
She spun toward the compass. Stared at it. Stared for a long time.
"Is that," she said slowly, "a Class Seven AI-spirit?"
"Class Eight, actually, and I find the downgrade offensive," Omen said pleasantly. "You must be the Ashveil girl. I was wondering when you'd show up."
Her name was Lyra. Lyra Ashveil, last of a bloodline that the schoolbooks listed as extinct — descendant of the Architect families who had survived the Collapse and gone underground, their heritage passed down through generations in fragments: half-understood spells, careful bloodline protections, and the bone-deep compulsion to find the Nexus Core that she'd had since childhood and never been able to explain.
She'd been tracking Architect signatures for three years.
"My grandmother told me about the Core," she said, sitting across the table from Kael with the wariness of someone who'd decided not to attack him only because Omen seemed to vouch for him, reluctantly, and with conditions. "She said finding it was the family's purpose. That there was something coming that only the Core could stop."
"Your grandmother was well-informed," Omen said.
"She's been dead for eight years." Lyra looked at the compass with something complex in her face. "She said to find the compass. She said it would explain what she couldn't."
Silence.
Then Lyra looked at Kael with an expression that was three-quarters hostile and one-quarter desperate. "So. You bonded the Engine. I need you to understand how deeply inconvenient that is for me."
"Yeah, I'm real torn up about your inconvenience," Kael said. He meant it to come out more neutral. "Look. I didn't choose this. But I have it, it bonded to me, and if what Omen says about Malgrath is true, then — we're both in danger. Like it or not."
A muscle in her jaw moved. She had lightning under her skin, he could see it with the visor — a constant low-level charge, like a storm system that never fully discharged. Wild. Intense. Barely managed.
"Malgrath," she said. "He's really moving?"
"He knows the Engine activated," Omen said. "He will be sending agents. Possibly already has."
Lyra closed her eyes briefly. When she opened them, she'd made a decision — he could see it, a door closing and another opening.
"Fine," she said. "We work together. Temporarily. Under very specific conditions."
"What conditions?" Kael asked.
"One: you do not touch my spellwork without asking. Two: if I say run, you run. Three: no heroic nonsense." She fixed him with a look that suggested she had strong experience with heroic nonsense and its consequences. "What do you bring to this? Other than the Core?"
He spread his hands to indicate the workshop.
She looked around at the pulse-glove, the scanner visor, the grapple-line launcher, the half-finished fourth project that was going to be an energy shield emitter, the schematics pinned to every available wall, the organized chaos of someone who had been solving problems with whatever materials they could find for their entire life.
Her expression shifted. Slightly. By about three degrees. Still hostile, but now with a layer of grudging reassessment.
"Okay," she said. "Not nothing."
"Thank you," Kael said, only mildly sarcastic.
"You're welcome," she said, completely without irony.
From the compass, Omen made a sound that was almost certainly a laugh, very carefully disguised as a cough.
That afternoon, the first of Malgrath's scouts reached Velturn City. Kael saw the signature on his visor — a dark resonance, wrong frequency, moving through the lower district like a shadow with a purpose. He and Lyra hit the roof together, and the fight was brief and chaotic and ended with a two-meter winged creature made of smoke and old bone dissolving into ash under the combined force of a Nexus pulse-blast and a bolt of storm lightning.
Standing in the aftermath, breathless, coats smoking, Lyra looked at him sideways.
"Not terrible," she said.
"High praise," he said.
Somewhere in the city below them, three more signatures appeared on his visor. And behind those, something vast and dark, moving slow and deliberate.
Something that hadn't bothered to hide