"Here, look," Asku said calmly, a twinkling fan of blue beams of light springing out from the cylindrical section in the centre of the drone's body. Each beam illuminated a spot on the walls or ceiling; there were even a couple on the floor.
Olivero bent over to study at one blue-lit spot low down on a stone wall. Just visible in the bright glare of the beam was a transparent patch a few millimetres across.
"What's that?" he asked.
"A bug," the drone said flatly, "An eavesdropping device. All of them. Broad-spectrum video and audio, with some chemical and subsonic capability as well. Very small, very sophisticated."
"How did you know it was there?" Seich demanded.
"I was looking for them," it replied, "Phage specifically designed me to do so."
"What?" Olivero shouted. Seich gasped, her hands covering her mouth in shock for the second time in fifteen minutes.
~I should have known it! Ngohan muttered in his own language.
"These things, they're all over the place," the drone went on, "Every planet and ship populated by anybody who would regard themselves as part of the Culture, and quite a few who are, currently, outside but might possibly join up in the future."
Olivero scratched at the transparent bug with a fingernail. He could not snag the edge of the device, or even feel its presence under his fingertip; it was barely visible in the harsh glare of the blue light still being emitted by the drone.
"Except for Phage Rock itself," Asku added, "Which has been systematically hunting down and removing alien surveillance kit from its own fabric and its visitors ever since it left the Tursen system thirty years ago."
"So how do we get rid of them?" the Professor demanded, looking directly at the drone for the first time.
"Allow me," it replied urbanely, then added more urgently, "Close your eyes and cover your face with your hands. Now!"
The humans complied at once, compelled - it seemed - by the sudden urgency in the drone's voice.
There was a blinding blue flash, like a thousand simultaneous lightning strikes in the small space of the study and visible even through closed eyelids, followed immediately by a smell compounded of overloaded circuits, flash-cooked organics and seared metal oxides that filled the space, causing the Professor to cough uncontrollably.
"And done," Asku said, sounding smug in exactly the same way, Seich noted, that Phage Rock did, "I do believe that we are now truly unobserved."
The Professor emitted what must have been a huge sigh of relief and somehow stood up straighter, looking around with some satisfaction and smiling broadly at the dozens of smoking black dots which now decorated his apartment.
~Is it really true? he muttered, apparently talking to himself.
~There is nothing, the drone responded, with a dryness which made its way unscathed through the other humans' translation devices, which is apparent to any of my senses which can now overhear us here.
"Well, it seems I should offer you my most profound thanks," Ngohan said formally, switching to Kurtursen, "Both for the privacy and for confirming my hypothesis after all these years."
Asku Trashaw dipped forward briefly, again making that drone bow.
Olivero stepped over to stand in front of Ngohan and made a formal bow in the Rotisivian style, looking only very slightly awkward to Seich's eyes.
"Professor, we have been informed that you have ideas, thoughts, research results," he said, "Which might be germane to the nature of the onlookers. Perhaps now would be the time and place to offer us your intelligence?"
"I had been studying the Books of the Onlookers," he began, in the style of one delivering an impromptu tutorial, "As have a great many other people, of course, but from the point of view of linguistic analysis, rather than trying to tease scientific or engineering concepts out of them."
He waved again at the stacked shelves of printed books.
"In studying their actual words, phrases, sentence structures, and so on, I have to accept that these are all a translation from the Onlookers' own language, but I have an hypothesis that the choice of words in Xlephic - and all the other languages in which the Books have appeared - might tell us something about the world-view of the Onlookers."
"Have you come to any conclusions?" Seich asked, speaking softly so as not to interrupt the man's train of thought.
The Professor barely acknowledged the question.
"The languages that we use are very different in many ways. Kurtursen, for example, is quite compact, matter-of-fact, even blunt, while Xlephic and, even more so, Rotisivian, expects a degree of embellishment in everyday informal speech, which explodes into extensive, florid, baroque language structures even in formal scientific writing: appeals to engage the reader, apologies for complexities or long-windedness, metaphors to amplify a viewpoint, etcetera, etcetera."
Both Olivero and Seich nodded. They had become very familiar with each other’s language over the last few years. Seich, in particular, found her thinking quite different when speaking Kurtursen.
"The metaphors used are particularly telling," Ngohan continued, "There are no metaphors based on common phenomena familiar to any of the kind of humans which now make up the Culture: nothing of the colours of sunrise or sunset, no comparisons with trees or plants, or animals or birds, or streams or rivers or oceans."
The Professor turned to look out of one of the windows.
"This, together with numerous other clues, leads me to suspect that the Onlookers are not based on a rocky planet like ours; that they are unfamiliar of the effects of land and water and air, and they are therefore not even remotely human."
There was a soft pop from behind them.
"You are, in fact," a deep voice said, "Entirely correct."