The word arbitration changed the air. It gave the evening a table it had to eat at.
The Prefecture inspector recovered first. She put her palms on the square of the table in front of the saint-face and moved it a precise inch left, as if adjusting a lens. "We will hear proposals," she said, "with witness present."
A rustle from the back—white moving without feet. The Dame Blanche had not been invited. Etiquette bowed to the fact that she did not require it. She leaned in the partial light, severity worn like kindness, eyes for ledgers, mouth for prices.
"Dame," the saint-face said, jammed halfway between obsequious and irritated. "We are discussing safety."
"You are practicing accounting with a river," she said. "I recommend a sharper pencil."
He held up the plan: sub-grade channels to coax Eau into municipal lines, valve gates to discourage seep, chalk-blessed sandbags at three known low points, and an oath for passage merchants to keep drains unblocked on penalty of collective fines. It was a cathedral built from paper and brass.
"What do you pay?" the Dame asked.
"Time saved, goods preserved—" he began.
She looked to Thomas instead. "You keep the ledger," she said, as if informing him of his job in case he'd missed it.
"On the river's side," he said.
"Then price them. Small costs now, or large later," she said. "Speak plain enough that even ink understands."
Thomas did math in a language that fit the night.
"If you force Eau into the municipal lines, the Catacombs collect surcharge: three days of bad luck measured in ankles, two shops losing floors to swelling, one child scared of stairs for a season," he said. "You get one avoided flood and two unexpected ones elsewhere. Ledger says Debt for redirection without consent."
The engineer colored in fury even clever men reserve for the obvious. "Water is a fluid, not a citizen."
"Then stop trying to make it sign forms," Michelle said.
The inspector hid a smile.
"Counter-proposal," Thomas said. "You want Eau to prefer the municipal route during storms? Make that route polite."
He touched the chalk map lightly, never on the river itself: three points along Eau where drain grates had a reputation for lying; a fourth where the passage floor dipped and kept secrets. "Cut three relief mouths—small, honest spillways—inside the municipal line that open before flood. Install hinged grates that don't bite and keep them clean. Chalk the thresholds, renew them before the tenth bell when heights steady. In exchange, Eau takes a promise: avoid passage floor Verre and Chant except for test flows on watch nights."
The saint-face laughed his pen back to his fingers. "You propose we pay in labor and attention."
"Yes," Thomas said. "They are cheaper than debt."
The Dame Blanche inclined her head the width of a kindness. "The river likes to be offered work, not worship," she said. "Is there a tithe?"
The chalk line of Eau shivered.
Sequana pressed a price into Thomas like a cold coin. You ask for relief. Pay in hours and openings.
"Payment," Thomas said, voice steady. "Three public work nights. Merchants, Syndics, Prefecture—hands in the same water. Grates are lifted, drains are scrubbed, trash is carried past three corners so it forgets its way back. A fourth night later: test flood—controlled, small—so Eau can check the work. After that, chalk renewed each month. Ledger credits: fewer panics; fewer drownings that almost happen; fewer chairs that learn to float."
The laborers nodded as if someone had remembered they exist. The glazier looked at his hands and found them willing.
The saint-face marshaled a final tactic: authority. "And if the river refuses?"
Michelle answered because answers given by girls with pamphlets have edges men are born without. "Then the river floods according to its own character and your signatures won't keep anyone dry."
"Madame Inspectrice," Thomas said, "public safety clause?"
She looked at the forms, then at the crowd, then at the chalk. "Public safety prefers solutions that cost sweat over those that cost neighbors," she said. "I'll stamp that. On one condition."
"Name it," the saint-face snapped, too quick to be wise.
"Witness must be present at the test flood," she said, eyes briefly on Thomas and then on Michelle. "Someone the arcade trusts to say if we cheated."
"Two witnesses," the Dame said. "One who writes, one who counts."
"Done," Michelle said, before her better sense could stop her mouth.
The saint-face saw control escaping like steam and reached for it. He grabbed the brass fork to make it obey him again. He struck it too hard. The tine sang an unpleasant interval; the chalk line of Eau lifted in a long, slow breath.
The floor shifted.
Not by much. Enough to demonstrate terms.
A thin tongue of water slid from nowhere and tested the toes of the square. It found a pamphlet that had fallen from Michelle's stack and tried to eat it. She plucked it up by a corner and held it like a flag.
"Public safety clause," she reminded the water, prim as a schoolmarm.
It snorted—if water can—and withdrew half a finger.
Thomas set Christian's pocket lamp on the table and rotated it until a clean line ran from flame to chalk to threshold. The Vitre Saint Fragment in his finger warmed. He did not use Lantern Thrust. He used the idea of it—a beam that behaved itself where everyone could see.
Light wrote a new boundary across Verre and Chant—not a wall; a promise. The rivulet tasted it and decided to be persuaded.
[SEQ] Lore — Public Oath (Eau): registered.
[SEQ] Effect: Relief mouths planned; test flood scheduled.
[SEQ] Note: Witness required for Gate unlock.
The saint-face began to sign because men hate being left behind more than they hate being wrong. The laborers signed because they intended to do the work anyway. The inspector stamped with the serious joy of a person allowed to stamp something that might save someone.
The Dame watched without moving. When signatures ended, she stepped forward and, with the side of her hand, rubbed a section of the chalk map until old lines faded and new ones kept their manners. "We have all made work," she said. "Do it."
The arcade considered clapping and decided it would be tacky.
Thomas exhaled for what felt like the first time that hour. He gathered the lamp. The two shadows near the pillar were still in agreement, soft and close, like a door partly ajar.
"Don't get greedy," he told his bones.
Michelle slid the brass key back into his hand. "Debt," she reminded, but the word smiled. "We'll pay in hours."
The Prefecture inspector shook his hand with the practical squeeze of people who carry buckets. "Eleventh bell for the test," she said. "If it goes badly, shout before anyone starts naming streets after problems."
The saint-face avoided Thomas's eyes and found his own pen endlessly fascinating. The engineer discovered that modesty comes in pocket sizes and tried one.
On their way out, the old chalk lady appeared from absolutely nowhere and added a discreet mark on the pillar—triangle and dot. "Good," she said to the air, to nobody, to Sequana. "Edges mind their work."
The pane took off its hat like a shy clerk.
[SEQ] Skill — Shadow Jump (I): Verified in public.
[SEQ] Cooldown: long. Range: short (contiguous shadows).
[SEQ] Synergies: Night Veil; Lantern geometry.
Outside, rain had chosen to be reasonable. The river ran its sums. The city held its breath for a beat and then decided not to.
Michelle tucked her arm through Thomas's like the younger partner in a law firm. "We'll need lists," she said. "Grates. Buckets. Chalk. Volunteers who like getting wet on purpose."
"Thibault likes all those things," Thomas said.
"He likes being brave in front of girls," she said.
"Just one," he thought, and did not say it.
They walked home with the lamp making a neat path at their feet. On the rooftops, gargouilles pretended not to gossip about boys who stepped between shadows. In the stones, a very old current approved of sweat as currency.
Sequana's voice—a pressure, a patience—touched his ribs. Credit for clean terms. Debt if you forget to show up to your own promises.
"I'll show," he said, under his breath.
He slept later with the knowledge that public had been introduced to river and had not been insulted by it. The ledger felt like a table set for more people than the house could hold—and ready anyway.