“But then how—” He stopped, and Kira could only guess what link data he was expressing now. “I was about to say, ‘How can you understand each other over the radio when half your communication is visual?’ but I suppose the link doesn’t transmit over the radio either, so we’re even there. But on the other hand, Partials can still understand each other in the dark.”

“I’ll grant you that,” said Kira, “but we also have a lot of verbal cues you don’t. Listen to these two sentences: ‘Are you going to eat that?’ Now: ‘Are you going to eat that?’”

Samm stared back, and Kira almost laughed at what she assumed was his confusion. “I suppose you’re going to tell me that the difference in volume changes the meaning of the sentence? We use the link for most forms of emphasis like that.”

“I suppose that gives us a leg up on radio communication,” said Kira, and waggled her eyebrows. “This may be the key to winning the war.”

Samm laughed, and Kira realized that laughter, at least, seemed to be fairly common among the Partials. They probably didn’t need it, since they could express enjoyment or humor through the link, but they still laughed anyway. Maybe it was built into some human segment of their custom genome? A vestigial response? “Enough about body language,” said Kira. “I want to practice the link, so hit me.”

“Hitting you won’t make the link easier to detect.”

“It’s an expression,” said Kira. “Send me some link data—start throwing it out there. I need to practice trying to pick it up.”

They spent the next few days practicing, with Samm sending her simple pheromonal messages and Kira trying everything she could to feel them, and to recognize which emotions they represented. A couple of times she thought she could sense it, but most of the time she was completely lost.