It was dark when Melusine slipped into the tent.

"Donald?"

"Shhh." I put a finger to her lips, drew her close to me. One hand slid slowly down her naked back, over a scrap of crushed velvet, and then back up and under her skirt to squeeze that elegant little ass. She raised her mouth to mine and we kissed deeply, passionately.

Then I tumbled her to the cot, and we began undressing each other. She ripped off three buttons tearing my shirt from me.

Melusine made a lot of noise, for which I was grateful. She was a demanding, self-centered lay, who let you know when she didn't like what you were doing and wasn't at all shy about telling you what to do next. She required a lot of attention. For which I was also grateful.

I needed the distraction.

Because while I was in his tent, screwing the woman he didn't want, Hawkins was somewhere out there getting killed. According to the operational report that I'd write later tonight, and received a day ago, he was eaten alive by an old bull rex rendered irritable by a painful brain tumor. It was an ugly way to go. I didn't want to have to hear it. I did my best to not think about it.

Credit where credit is due -- Melusine practically set the tent ablaze. So I was using her. So what? It was far from the worst of my crimes. It wasn't as if she loved Hawkins, or even knew him for that matter. She was just a spoiled little rich-bitch adventuress looking for a mental souvenir. One more notch on her diaphragm case. I know her type well. They're one of the perks of the business.

There was a freshly prepared triceratops skull by the head of the bed. It gleamed faintly, a pale, indistinct shape in the darkness. When Melusine came, she grabbed one of its horns so tightly the skull rattled against the floorboards.

Afterwards, she left, happily reeking of bone fixative and me. We'd each had our little thrill. I hadn't spoken a word during any of it, and she hadn't even noticed.

T. rex wasn't much of a predator. But then, it didn't take much skill to kill a man. Too slow to run, and too big to hide -- we make perfect prey for a tyrannosaur.

When Hawkins' remains were found, the whole camp turned out in an uproar. I walked through it all on autopilot, perfunctorily giving orders to have Satan shot, to have the remains sent back uptime, to have the paperwork sent to my office. Then I gathered everybody together and gave them the Paradox Lecture. Nobody was to talk about what had just happened. Those who did would be summarily fired. Legal action would follow. Dire consequences. Penalties. Fines.

And so on.

It was two a.m. when I finally got back to my office, to write the day's operational report.

Hawkins's memo was there, waiting for me. I'd forgotten about that. I debated putting off reading it until tomorrow. But then I figured I was feeling as bad now as I was ever going to. Might as well get it over with.

I turned on the glow-pad. Hawkins' pale face appeared on the screen. Stiffly, as if he were confessing a crime, he said, "My folks didn't want me to become a scientist. I was supposed to stay home and manage the family money. Stay home and let my mind rot." His face twisted with private memories. "So that's the first thing you have to know -- Donald Hawkins isn't my real name.

"My mother was kind of wild when she was young. I don't think she knew who my father was. So when she had me, it was hushed up. I was raised by my grandparents. They were getting a little old for child-rearing, so they shipped me back-time to when they were younger, and raised me alongside my mother. I was fifteen before I learned she wasn't really my sister.

"My real name is Philippe de Cherville. I swapped table assignments so I could meet my younger self. But then Melusine -- my mother -- started hitting on me. So I guess you can understand now -- " he laughed embarrassedly -- "why I didn't want to go the Oedipus route."

The pad flicked off, and then immediately back on again. He'd had an afterthought. "Oh yeah, I wanted to say ... the things you said to me today -- when I was young -- the encouragement. And the tooth. Well, they meant a lot to me. So, uh ... thanks."

It flicked off.

I put my head in my hands. Everything was throbbing, as if all the universe were contained within an infected tooth. Or maybe the brain tumor of a sick old dinosaur. I'm not stupid. I saw the implications immediately.

The kid -- Philippe -- was my son.

Hawkins was my son.

I hadn't even known I had a son, and now he was dead.

A bleak, blank time later, I set to work drawing time lines in the holographic workspace above my desk. A simple double-loop for Hawkins/Philippe. A rather more complex figure for myself. Then I factored in the TSOs, the waiters, the paleontologists, the musicians, the workmen who built the station in the first place and would salvage its fixtures when we were done with it ... maybe a hundred representative individuals in all.

When I was done, I had a three-dimensional representation of Hilltop Station as a node of intersecting lives in time. It was one hell of a complex figure.

It looked like the Gordian knot.

Then I started crafting a memo back to my younger self. A carbon steel, razor-edged, Damascene sword of a memo. One that would slice Hilltop Station into a thousand spasming paradoxical fragments.

Hire him, fire her, strand a hundred young scientists, all fit and capable of breeding, one million years B.C. Oh, and don't father any children.

It would bring our sponsors down upon us like so many angry hornets. The Unchanging would yank time travel out of human hands -- retroactively. Everything connected to it would be looped out of reality and into the disintegrative medium of quantum uncertainty. Hilltop Station would dissolve into the realm of might-have-been. The research and findings of thousands of dedicated scientists would vanish from human knowing. My son would never have been conceived or born or sent callously to an unnecessary death.

Everything I had spent my life working to accomplish would be undone.

It sounded good to me.

When the memo was done, I marked it PRIORITY and MY EYES ONLY. Then I prepared to send it three months back in time.

The door opened behind me with a click. I spun around in my chair. In walked the one man in all existence who could possibly stop me.

"The kid got to enjoy twenty-four years of life, before he died," the Old Man said. "Don't take that away from him."

I looked up into his eyes.

Into my own eyes.

Those eyes fascinated and repulsed me. They were deepest brown, and nested in a lifetime's accumulation of wrinkles. I've been working with my older self since I first signed up with Hilltop Station, and they were still a mystery to me, absolutely opaque. They made me feel like a mouse being stared down by a snake.

"It's not the kid," I said. "It's everything."

"I know."

"I only met him tonight -- Philippe, I mean. Hawkins was just a new recruit. I barely knew him."

The Old Man capped the Glenlivet and put it back in the liquor cabinet. Until he did that, I hadn't even noticed I was drinking. "I keep forgetting how emotional I was when I was young," he said.

"I don't feel young."

"Wait until you're my age."

I'm not sure how old the Old Man is. There are longevity treatments available for those who play the game, and the Old Man has been playing this lousy game so long he practically runs it. All I know is that he and I are the same person.

My thoughts took a sudden swerve. "God damn that stupid kid!" I blurted. "What was he doing outside the compound in the first place?"

The Old Man shrugged. "He was curious. All scientists are. He saw something and went out to examine it. Leave it be, kid. What's done is done."