"They're so strange." She looks wistful for a moment. "But after a generation I got . . . sad." Another sip. "I was living among them to study them, you see. And when you live among people for gigaseconds on end you can't stop yourself getting involved, not unless you go totally post and upgrade your—well. I made friends and watched them grow old and die until I couldn't take any more. I had to come back and excise the . . . the impact. The pain."

Gigaseconds? Thirty planetary years each. That's a long time to spend among aliens. She's studying me intently. "That must have been very precise surgery," I say slowly. "I don't remember much of my previous life."

"You were human, though," she prods.

"Yes." Emphatically yes. Shards of memory remain: a flash of swords in a twilit alleyway in the remilitarized zone. Blood in the fountains. "I was an academic. A member of the professoriat." An array of firewalled assembler gates, lined up behind the fearsome armor of a customs checkpoint between polities. Pushing screaming, imploring civilians toward a shadowy entrance—"I taught history." That much is—was—true. "It all seems boring and distant now." The brief flash of an energy weapon, then silence. "I was getting stuck in a rut, and I needed to refresh myself. I think."

Which is almost but not quite a complete lie. I didn't volunteer, someone made me an offer I couldn't refuse. I knew too much. Either consent to undergo memory surgery, or my next death would be my last. At least, that's what it said I'd done in the dead-paper letter that was waiting by my bedside when I awakened in the rehab center, fresh from having the water of Lethe delivered straight to my brain by the molecular-sized robots of the hospitaler surgeon-confessors. I grin, sealing the partial truths with an outright lie. "So I had a radical rebuild, and now I can't remember why."