Like when they’re in a big rush.

The wall said:

so pRetty i hAd to Eat hiM

I crossed to the wall. The darker layer was less noticeable up close. I ran my fingertips across the letters. The cheap water-based paint felt as dry as a piece of chalk.

With one fingernail, I incised a curved mark in the paint, about the size of a fully grown hookworm. The dark color showed through a little more clearly there.

I brought my fingertip to my nose and sniffed.

“Dude, that’s weird,” Roger said.

“Smell is the most sensitive of our senses, Roger,” I said. But I didn’t mention the substance humans are most sensitive to: ethyl mercaptan, the odorant that gives rotten meat its particular tang. Your nose can detect one four-billionth of a gram of it in a single breath of air.

My nose is about ten times better.

I also didn’t mention to Roger that my one little sniff had made me certain of something—the words had been painted in blood.

It turned out to be more than blood, though. As I incised the wall again with my steel-hard fingernails, breathing in the substances preserved under the hasty coat of paint, I caught a whole range of tissues from the human body. The iron tang of blood was joined by the mealy smell of ground bone, the saltiness of muscle, the flat scent of liver, and the ethyl mercaptan effluence of skin tissues.

I believe the layman’s term is gristle.

There were other, sharper smells mixed in—chemical agents used to clean away the message. By the time they’d found it, though, the blood must have already soaked deep into the plaster, where it still clung tenaciously. They had painted it over, but the letters remained.

I mean, really: water-based paint? What is it with New York landlords?

“What the hell are you doing?” Lace said softly.

I turned and saw that they were all sitting there wide-eyed. I tend to forget how normal humans are made uncomfortable by the sniffing thing.

“Well…” I started, searching for a good excuse among the dregs of rum in my system. What was I going to say?

The buzzer sounded.

“Pizza’s here!” Roger cried, jumping up and running to the door.

“Sounds good to me,” I said.

For some reason, I was starving.

Ants have this religion, and it’s caused by slimeballs.

It all starts with a tiny creature called Dicrocoelium dendriticum—though even parasite geeks don’t bother saying that out loud. We just call them “lancet flukes.”

Like a lot of parasites, these flukes start out in a stomach. Stomachs are the most popular organs of final hosts, you may have noticed. Well, duh—there’s food in them. In this case, we’re talking about the stomach of a cow.

When the infected cow makes a cow pie, as we say in Texas, a passel of lancet fluke eggs winds up in the pasture. A snail comes along and eats some of the cow pie, because that’s what snails do. Now the snail is infected. The fluke eggs hatch inside the unlucky snail’s belly and then start to drill their way out through its skin.

Fortunately for the snail, it has a way to protect itself: slime.

The sliminess of the snail’s skin lubricates the flukes as they drill their way out, and the snail survives their exit. By the time the flukes escape, they’re entirely encased in a slimeball, unable to move. They’ll never mess with any snails again, that’s for sure.

But the flukes don’t mind this turn of events. It turns out they wanted to be covered in slime. The whole trip through the snail was just evolution’s way of getting the flukes all slimy. Because they’re headed to their next host: an ant.

Here’s something you didn’t want to know: Ants love slimeballs.

Slimeballs make a delicious meal, even when they have a few hundred flukes inside. So sooner or later, some unlucky ant comes along, eats the slimeball, and winds up with a bellyful of parasites.

Inside the ant, the lancet flukes quickly organize themselves. They get ready for some parasite mind control.

“Do ants even have minds?” you may ask. Hard to say. But they do have tiny clusters of nerves, about midway in complexity between human brains and TV remote controls. A few dozen flukes take up a position at each of these nerve clusters and begin to change the ant’s behavior.

The flukey ant gets religion. Sort of.

During the day, it acts normal. It wanders around on the ground, gathering food (possibly more slimeballs) and hanging out with the other ants. It still smells healthy to them, so they don’t try to drive it off as they would a sick ant.

But when night falls, the ant does something flukey.

It leaves the other ants behind and climbs up a tall blade of grass, getting as high as it can off the ground. Up there under the stars, it waits all night alone.

What does it think it’s doing? I always wonder.

Ants may not think anything ever. But if they do, maybe they have visions of strange creatures coming along to carry them to another world, like X-Files geeks in the Roswell desert waiting for a spaceship to whisk them away. Or perhaps Dicrocoelium dendriticum really is a religion, and the ant thinks some great revelation will strike if it just spends enough nights up at the top of a blade of grass. Like a swami meditating on a mountain, or a monk fasting in a tiny cell.

I’d like to think that in its final moments the ant is happy, or at least relieved, when a cow’s mouth comes chomping down on its little blade of grass.

I know the flukes are happy. They’re back in a cow’s stomach, after all.

Parasite heaven.

I didn’t really sleep that night. I never do.

Sure, I take my clothes off, get into bed, and close my eyes. But the whole unconsciousness thing doesn’t quite happen. My mind keeps humming, like in those hours when you’re coming down with something—not quite sick yet, but a bit light-headed, a fever threatening, illness buzzing at the edge of your awareness like a mosquito in the dark.

The Shrink says it’s the sound of my immune system fighting the parasite. There’s a war in my body every minute, a thousand T-and B-cells battering the horned head of the beast, prying at its hooks along my muscles and spine, finding and destroying its spores hidden inside transmuted red blood cells. On top of which there’s the parasite fighting back, reprogramming my own tissues to feed it, tangling up my immune defenses with false alarms and bogus enemies.

This guerrilla war is always going on, but only when I’m lying in silence can I actually hear it.

You’d think this constant battle would tear me apart, or leave me exhausted come daylight, but the parasite is too well made for that. It doesn’t want me dead. I’m a carrier, after all—I have to stay alive to ensure its spread. Like every parasite, the thing inside me has evolved to find a precarious balance called optimum virulence. It takes as much as it can get away with, sucking out the nutrients it needs to create more offspring. But no parasite wants to starve the host too quickly, not while it’s getting a free ride. So, as long as it gets fed, it backs off. I may eat like a four-hundred-pound guy, but I never get fat. The parasite uses the nutrients to churn out its spores in my blood and saliva and semen, with enough left over to give me predatory strength and hyped-up senses.

Optimum virulence is why most deaths from parasites are long and lingering—in the case of a carrier like me, the time it takes to die happens to be longer than a normal human life span. That’s the way the older peep hunters talk about it: not so much immortality as a centuries-long downward spiral. Maybe that’s why they use the word undead.