"I used to make the Channer run a lot. Pharmaceutical dives, supply trips to Beebe, ecotourism. A while back I shuttled some corpse type out to Beebe; he said he was staying for a month or so. The GA calls me three days later and tells me to go pick him up. I show up for the run and they tell me it's cancelled. No explanation."

"Pretty strange," Jarvis remarks.

"You're the first run I've had to Channer in six weeks. You're the first run anyone's had, from what I can tell. So, you pull some weight."

"Not really." Jarvis shrugs in the half-light. "I'm just a research associate. I go where they tell me, just like you. Today they told me to go and pick up an order of fish to go."

Joel looks at him.

"You were asking why they got so big," Jarvis says, deking to the right. "We figure it's some kind of endosymbiotic infection."

"No shit."

"Say it's easier for some microbe to live inside a fish than out in the ocean — less osmotic stress — so once inside it's pumping out more ATP than it needs."

"ATP," Joel says.

"High-energy phosphate compound. Cellular battery. Anyway, it spits out this surplus ATP, and the host fish can use it as extra growth energy. So maybe Channer Vent's got some sort of unique bug that infects teleost fishes and gives 'em a growth spurt."

"Pretty weird."

"Actually, happens all the time. Every one of your own cells is a colony, for that matter. You know, nucleus, mitochondria, chloroplasts if you're a plant—"

"I'm not." More than I can say for some folks...

"—those all used to be free-living microbes in their own right. A few billion years ago something ate them, but it couldn't digest them properly so they all just kept living inside the cytoplasm. Eventually they struck up a deal with the host cell, took over housecleaning tasks and suchlike in lieu of rent. Voila: your modern eukaryotic cell."

"So what happens if this Channer bug gets into a person? We all grow three meters high?"

A polite laugh. "Nope. People stop growing when they reach adulthood. So do most vertebrates, actually. Fish, on the other hand, keep growing their whole lives. And deepwater fish—those don't do anything except grow, if you know what I mean."

Joel raises his eyebrows.

Jarvis holds up his hands. "I know, I know. Your baby finger is bigger than your average deepsea fish. But that just means they're short of fuel; when they do gas up, believe me, they use it for growth. Why waste calories just swimming around when you can't see anything anyway? In dark environments it makes more sense for predators to sit-and-wait. Whereas if you grow big enough, maybe you'll get too big for other predators, you see?"

"Mmm."