Centuries ago some SETI messages had introduced humans to the slow-motion galactic economy. Many SETI signals were funeral notices or religious recruitments, brags and laments, but some sent autonomous AI agents as part of the hierarchical software. These were indeed agents in the commercial sense, able to carry out negotiations. They sought exchange of information at a “profit” that enabled them to harvest what they liked from the emergent human civilization. The most common “cash” was smart barter, with the local AI agent often a hard negotiator—tough-minded and withholding. Indeed, this sophisticated haggling had opened a new window onto the rather stuffy cultural SETI transmissions. Some alien AIs loved to quibble; others sent peremptory demands. Some offers were impossible to translate into human terms. This told the Librarians and xenoists much, by deftly reading between the lines—when possible at all.

“Then why summon me?” Might as well be direct, look him in the eye, complete with skeptical tilt of mouth. She had used no makeup, of course, and wore the full-length gown without belt, as was traditional. She kept her hands still, though they wanted to fidget under the Prefect’s hard gaze.

“None of what he found explains his behavior.” The Prefect turned and waved at a screen. It showed color-coded sheets of array configurations—category indices, depth of Shannon content, transliterations, the usual. “He interacted with the data slabs in a familiarization mode of the standard kind.”

“But nothing about this incident seems standard,” she said, to be saying something, needling him.

“Indeed.” A scowl, fidgeting hands. “Yesterday he left the immersion pod we gave him permission to use, above his station as a Hound. He went first to his apartment. His suite mate was not there and Ajima spent about an hour. He smashed some furniture and ate some food. Also opened a bottle of a high-alcohol product whose name I do not recognize.”

“Standard behavior when coming off watch, except for the furniture,” she said.

He showed no reaction. Lightness was not the right approach here. Ignoring the failed joke, with an eyebrow flicker he said, “His friends say he had been depressed, interspersed with bouts of manic behavior. This final episode took him over the edge.”

Literally, Rachel thought. “Did you ask the Sigma Structures AI?”

“It said it had no hint of this, this…”

“Suicidal craziness.”

“Yes. In my decades of experience, I have not seen such as this. It is difficult work we do, with digital intelligences behind which lie minds utterly unlike ours.” The Prefect steepled his fingers sadly. “We should never assume otherwise.”

“I’ll be on guard, of course. But… why did Ajima bother with the Sigma Structures at all?”

A small shrug. “They are a famous uncracked problem and he was fresh, bright. You too have shown a talent for the unusual.” He smiled, which compared to the other Prefects was like watching the sun come out from behind a cloud. She blinked, startled. “My own instinct says there is something here of fundamental interest… and I trust you to be cautious.”