Siban arrived exactly when he'd said he would.
Batu had noticed the pattern in the administrative records days earlier, though at the time he hadn't known what to make of it. Supply requests submitted before their deadlines. Inspection reports filed the morning they were due instead of late that night.
That kind of consistency could mean discipline. It could also mean calculation. A man who handled his paperwork carefully understood that records shaped reputation, and Batu had learned not to trust reputation until he'd tested it against behavior.
Siban looked to be around thirty. Lean-faced. Controlled. He carried himself like someone used to negotiations, where a careless expression could cost more than a missed order.
He sat across from Batu without waiting for permission.
Batu marked it immediately. Confidence, perhaps. Or an attempt to place himself as an equal.
Siban's aide withdrew from the tent before either man spoke again.
The breakfast itself was ordinary camp food. Flatbread. Grain porridge. Watered ale. Neither man wasted time commenting on it.
Siban looked over the food before speaking.
"The northeastern detachment submitted a grain request last week. I wanted to mention it directly. The eastern pasture stores are lower than the current tally indicates. One of the supply riders counted the autumn allocation incorrectly."
So that was the opening. Administrative. Useful. Safe.
"Orel has the request already," Batu said. "He'll send a rider to verify the recount before he approves anything."
Siban nodded once. He poured himself a drink from the pitcher, then set it back at the center of the table without offering any to Batu.
Another small signal. Not openly hostile. Just careful.
"I heard the Sarat action ended well," Siban said. "Nine hundred and forty against five hundred. Most commanders would call that favorable odds."
"It achieved what it needed to achieve."
Siban watched him with mild interest. Not surprised by the answer. Confirmed by it.
"The western clans have started talking," he said. "The Burjin elder sent a rider to the Ulus headman two weeks ago. Word about Kirsa spread before your column even returned."
That timing mattered. Rumors moving ahead of military reports meant organized communication, not camp gossip.
"What are they saying?"
"That you kept a Merkid commander alive without chaining him."
Siban tore off a piece of flatbread.
"Some of the clans think it's interesting. Others don't like it. Mostly older officers. Men whose fathers fought the Merkid campaigns."
Batu watched him while he ate.
The information checked out. More importantly, the framing stayed neutral. Siban wasn't steering toward a conclusion. He was establishing credibility by offering information Batu could verify.
A careful opening move.
"The administrative changes have people talking too," Siban continued. "The written rulings. The toll guarantee for the Bulgar merchant."
A slight pause.
"It's different from the way we've handled things before."
"Yes."
"The northeastern sub-commanders have been asking what it means for tribute collection." Siban kept his tone conversational. "Whether the written-ruling system applies to their territories as well, or only to the western clans."
"It applies everywhere. Tell them that."
Siban nodded immediately.
Too quickly.
He'd asked the question like a man seeking clarification, but he already knew the answer. Batu could hear it in the rhythm of the exchange. Which meant Siban had been discussing the administrative changes with someone who had direct access to command-level discussions.
They continued eating, each man using the meal as cover while they measured the other.
"Mersek's boundary dispute," Siban said casually. "I heard it was resolved yesterday."
There it was.
The name arrived in the middle of the conversation, placed carefully between ordinary subjects so it would sound accidental. Batu understood the tactic at once. Siban wanted to see whether the name produced a reaction.
"It was resolved."
"Mersek's capable." Siban refilled his cup. "His unit stays organized. I've spoken with him a few times while traveling through the northeastern sector. He understands the supply vulnerabilities between here and the Irtysh better than most officers."
Batu felt the pieces begin to lock together.
Supply vulnerabilities. The northeastern route. The road controlled by Siban's own detachment.
"When was the last time you traveled through the northeastern sector?"
"Five weeks ago. Before I arrived here."
Siban met his eyes evenly, as though he'd expected the question.
"Routine inspection of the border positions."
Five weeks.
That had been before Sarat. Before Kirsa's capture. Before the confirmation from the Borte-Qol channel. Before Batu reviewed the operational records and found Mersek's name tied to them.
So Siban and Mersek had contact before any investigation began.
Batu broke apart another piece of flatbread, buying himself a moment to think.
"How familiar are you with the Tergesh tributary terms?"
Siban answered immediately.
"Standard tribute structure. A penalty levy of one hundred horses. Road passage rights for supply trains moving through Tergesh territory."
He recited it smoothly, like a man repeating written material.
Batu focused on the final point.
"The road passage clause was added later," he said. "It wasn't part of the original agreement."
The clause mattered because almost nobody should have known about it.
Batu lowered his eyes to the table while the implications settled into place again.
The road-passage addition had only been discussed inside the command tent the night before the Tergesh operation. Five men present. Torghul. Khulgen. Odun. Two senior council officers. One of them had been Mersek.
The clause had never entered the general summaries. It hadn't moved through ordinary camp channels. Kirsa had already confirmed the mystery rider knew about it, and Batu had traced that leak back toward Mersek.
Now Siban had repeated the clause over breakfast as though it were routine administrative knowledge.
It wasn't.
Batu kept his expression steady. No reaction. No visible change.
He finished the bread before speaking again.
"The tributary agreements are being standardized across the western clans. If your officers need the full records, Orel has them."
"I'll direct them to him."
The meal continued another ten minutes.
Siban asked two additional questions, both legitimate administrative concerns. Batu answered both without hesitation.
On the surface, the conversation never changed tone. Two officers discussing logistics over breakfast. Calm. Functional. Entirely ordinary.
When the meal ended, Siban stood and offered exactly the proper amount of gratitude. Respectful without sounding submissive.
His aide appeared at the entrance almost immediately, suggesting he'd been waiting nearby for a signal.
"It's good to finally meet properly," Siban said. "I'd intended to introduce myself before the Sarat campaign."
"I'm glad you did."
Siban inclined his head, then left the tent.
Batu remained seated for several moments after he was gone.
He reviewed the conversation piece by piece, the same way he would review a battlefield report.
Siban knew about the road-passage clause.
Siban had spoken with Mersek five weeks earlier, before anyone suspected the command quarter had been compromised.
Siban had deliberately introduced Mersek's name during the meal to test Batu's reaction.
And Siban had arrived now. After Sarat. After Kirsa. After the western clans began reacting to Batu's decisions.
That timing removed coincidence.
The Mersek problem was larger than one officer passing information carelessly.
Siban had been building access long enough to obtain operational details from inside the command structure itself. Which meant the eastern network had reached deeper, and earlier, than Batu had assumed.
Batu stood and crossed to the tent entrance.
Outside, the camp had settled into its morning routines. Torghul's training cadre was already drilling on the eastern flat. Men moved along the horse lines distributing feed and checking tack assignments for the day.
Siban's aide was walking toward the eastern officer quarters at a measured pace. Either Siban had already gone ahead, or he was meeting someone before returning to his detachment.
A disciplined administrator. Careful records. Prior contact with Mersek. Knowledge of restricted operational clauses.
None of it proved guilt by itself.
Together, it formed a pattern.
Batu found Khulgen inside the command tent.
"I need information introduced into the camp's rumor flow today," Batu said. "Something that reaches Mersek before the evening meal. Something that gives him a reason to act tonight instead of waiting."
Khulgen studied him briefly. He didn't waste time asking why the timeline had changed.
"What kind of information?"
"Something that makes remaining still feel dangerous. Not a threat. A development. If it sounds planted, he won't move."
Khulgen considered that for several seconds.
Then he said, "Temur."
Batu looked at him, waiting.
"Temur's been sitting in the eastern holding pen for two months," Khulgen said. "If word spreads that his situation is under review, and that command intends to decide his fate this week, anyone worried about what Temur knows would panic."
He folded his arms.
"A man can ignore a prisoner. He can't ignore the possibility of questioning."
Batu considered the logic.
Temur had already named Guyuk once. If Mersek was feeding information eastward, then Temur becoming relevant again created immediate danger. A renewed investigation could produce more names. More links in the chain.
Possibly Mersek himself.
"Let the rumor spread naturally," Batu said. "Use supply rotation talk. Nothing direct."
Khulgen nodded once and left the tent.
Batu remained where he was, looking across the central camp grounds toward the eastern officer quarters.
Somewhere over there, Siban was moving through the camp. Inspecting something. Speaking with someone. Continuing to behave like a reasonable, capable officer with no obvious flaws.
But the connections were there now.
Mersek. The road-passage clause. The mystery rider who reached Kirsa before the Sarat coalition assembled.
The network had structure. Coordination. Time.
Before nightfall, Temur's name would begin circulating through the camp.
By tomorrow morning, Batu would know whether Mersek intended to stay in place or run.
Batu already suspected he knew the answer.