"You can be so—so brutal sometimes," she was saying. "I know you don't mean to be, but… I don't know. Maybe I'm your pressure-release valve, or something. Maybe you have to submerge yourself so much on the job that everything just, just builds up and you need some kind of punching bag. Maybe that's why you say the things you do."

She was waiting for me to say something now. "I've been honest," I said.

"Yeah. Pathologically. Have you ever had a negative thought that you haven't said out loud?" Her voice trembled but her eyes—for once— stayed dry. "I guess it's as much my fault as yours. Maybe more. I could tell you were—disconnected, from the day we met. I guess on some level I always saw it coming."

"Why even try, then? If you knew we were just going to crash and burn like this?"

"Oh, Cygnus. Aren't you the one who says that everyone crashes and burns eventually? Aren't you the one who says it never lasts?"

Mom and Dad lasted. Longer than this, anyway.

I frowned, astonished that I'd even let the thought form in my head. Chelse read the silence as a wounded one. "I guess—maybe I thought I could help, you know? Help fix whatever made you so—so angry all the time."

The butterfly was starting to fade. I'd never seen that happen before.

"Do you understand what I'm saying?" she asked.

"Sure. I'm a fixer-upper."

"Siri, you wouldn't even get a tweak when I offered. You were so scared of being manipulated you wouldn't even try a basic cascade. You're the one guy I've met who might be truly, eternally unfixable. I dunno. Maybe that's even something to be proud of."

I opened my mouth, and closed it.

She gave me a sad smile. "Nothing, Siri? Nothing at all? There was a time you always knew exactly what to say." She looked back at some earlier version of me. "Now I wonder if you ever actually meant any of it."

"That's not fair."

"No." She pursed her lips. "No, it isn't. That's not really what I'm trying to say. I guess…it's not so much that you don't mean any of it. It's more like you don't know what any of it means."

The color was gone from the wings. The butterfly was a delicate charcoal dusting, almost motionless.

"I'll do it now," I said. "I'll get the tweaks. If it's that important to you. I'll do it now."

"It's too late, Siri. I'm used up."

Maybe she wanted me to call her back. All these words ending in question marks, all these significant silences. Maybe she was giving me the opportunity to plead my case, to beg for another chance. Maybe she wanted a reason to change her mind.

I could have tried. Please don't, I could have said. I'm begging you. I never meant to drive you away completely, just a little, just to a safer distance. Please. In thirty long years the only time I haven't felt worthless was when we were together.

But when I looked up again the butterfly was gone and so was she, taking all baggage with her. She carried doubt, and guilt for having led me on. She left believing that our incompatibility was no one's fault, that she'd tried as hard as she could, even that I had under the tragic weight of all my issues. She left, and maybe she didn't even blame me, and I never even knew who'd made that final decision.

I was good at what I did. I was so damned good, I did it without even meaning to.

"My God! Did you hear that!?"

Susan James bounced around the drum like a pronking wildebeest in the half-gravity. I could see the whites of her eyes from ninety degrees away. "Check your feeds! Check your feeds! The pens!"

I checked. One scrambler afloat; the other still jammed into its corner.

James landed at my side with a two-footed thump, wobbling for balance. "Turn the sound up!"

The hissing of the air conditioners. The clank of distant machinery echoing along the spine; Theseus usual intestinal rumblings. Nothing else.

"Okay, they're not doing it now." James brought up a splitscreen window and threw it into reverse. "There," she pronounced, replaying the record with the audio cranked and filtered.

In the right side of the window, the floating scrambler had drifted so that the tip of one outstretched arm brushed against the wall that adjoined the other pen. In the left side, the huddled scrambler remained unmoving.

I thought I heard something. Just for an instant: the brief buzz of an insect, perhaps, if the nearest insect hadn't been five trillion kilometers away.

"Replay that. Slow it down."

A buzz, definitely. A vibration.

"Way down."

A click train, squirted from a dolphin's forehead. Farting lips.

"No, let me." James bulled into Cunningham's headspace and yanked the slider to the left.

Tick tick…tick…tick tick tick…tick…tick tick tick…

Dopplered down near absolute zero, it went on for almost a minute. Total elapsed real time was about half a second.

Cunningham zoomed the splitscreen. The huddled scrambler had remained motionless, except for the rippling of its cuticle and the undulation of its free arms. But before I'd only seen eight arms—and now I could make out the bony spur of a ninth peeking from behind the central mass. A ninth arm, curled up and hidden from view, tick tick ticking while another creature casually leaned against the other side of the wall…

Now, there was nothing. The floating scrambler had drifted aimlessly back to the center of its enclosure.

James's eyes shone. "We've got to check the rest of—"

But Theseus had been watching, and was way ahead of us. It had already searched the archives and served up the results: three similar exchanges over two days, ranging in duration from a tenth of a second to almost two.

"They're talking," James said.

Cunningham shrugged, a forgotten cigarette burning down between his fingers. "So do a lot of things. And at that rate of exchange they're not exactly doing calculus. You could get as much information out of a dancing honeybee."

"That's nonsense and you know it, Robert."

"What I know is that—"

"Honeybees don't deliberately hide what they're saying. Honeybees don't develop whole new modes of communication configured specifically to confound observers. That's flexible, Robert. That's intelligent."

"And what if it is, hmm? Forget for a moment the inconvenient fact that these things don't even have brains. I really don't think you've thought this through."

"Of course I have."

"Indeed? Then what are you so happy about? Don't you know what this means?"

Sudden prickling on the back of my neck. I looked around; I looked up. Jukka Sarasti had appeared in the center of the drum, eyes gleaming, teeth bared, watching us.

Cunningham followed my gaze, and nodded. "I'd wager it does…"

There was no way to learn what they'd whispered across that wall. We could recover the audio easily enough, parse every tick and tap they'd exchanged, but you can't decipher a code without some idea of content. We had patterns of sound that could have meant anything. We had creatures whose grammar and syntax—if their mode of communication even contained such attributes—were unknown and perhaps unknowable. We had creatures smart enough to talk, and smart enough to hide that fact. No matter how much we wanted to learn, they were obviously unwilling to teach us.

Not without—how had I put it? — negative reinforcement.

It was Jukka Sarasti who made the decision. We did it on his orders, as we did everything else. But after the word had come down— after Sarasti had disappeared in the night and Bates had retreated down the spine and Robert Cunningham had returned to his studies at the back of the drum—I was the one Susan James was left with. The first to speak the vile thought aloud, the official witness to posterity. I was the one she looked at, and looked away from, her surfaces hard and refractory.