The coffee had gone cold again.
Ethan surfaced to find his apartment dark except for the Engine's faint luminescence and the laptop screen's accusatory glow. The clock read 3:47 AM. He'd lost six hours to thirty-seven millennia of bacterial politics.
His left hand cramped around the mug. He set it down carefully, watching the tremor migrate up his forearm like a separate creature testing the limits of its territory. The ALS clinic had given him eighteen months, maybe two years before the breathing went. Dr. Reeves had used the phrase "progressive deterioration" as if clinical distance could soften the mathematics of muscle death.
But the Engine had shown him something else entirely: time as negotiable currency, vitality as exchangeable resource. Abel's journal suggested he'd burned decades of life pushing Aethon past its early bottlenecks. Hemorrhaged his own cells to jumpstart theirs.
Ethan had no decades to burn. But he had months that might stretch into centuries, if he spent them carefully.
He stood, testing his balance, and crossed to the window. Cambridge stretched below—streetlights casting amber pools on wet pavement, a lone taxi threading through empty intersections. Real people living real minutes that accumulated into ordinary hours.
The Engine pulsed once behind him. Invitation or reminder.
He turned back.
---
On Aethon, the stromatolite cities had discovered warfare.
Not intentional. Nothing about microbial mats suggested strategy or malice. But two mega-colonies had reached critical mass in adjacent shallows, and their chemical signaling had begun to interfere—growth hormones from one population triggering defensive responses in the other, toxins meant to clear space creating dead zones that neither could colonize.
The boundary between them had become a waste: three hundred miles of sterilized sediment where nothing grew.
Ethan watched the stalemate calcify over twelve thousand years. Both colonies slowed their expansion. Both developed thicker biofilms, better toxin resistance, more conservative growth patterns. Both survived, but barely, locked in equilibrium that wasted energy on mutual destruction.
He could fix it. One intervention—a current shift, a temperature gradient, anything to break the symmetry and let one colony dominate cleanly. The loser would die but the winner would flourish, and in ten thousand years the diverse genetic material would seed new experiments.
His hand moved toward the Engine's surface.
Stopped.
The covenant wasn't about watching everything. It was about watching *everything*—including his own impulse to interfere. Including the calculations that made intervention feel efficient, necessary, kind.
He pulled back.
The stalemate continued. Neither colony advanced.
---
Maya called at 9 AM, which meant Ethan had been gone seven hours subjective but sixty-two thousand years objective.
"You missed the seminar," she said without preamble. "Kovacs presented his quantum foam results. Half the department thinks he's solved the fine-tuning problem."
Ethan blinked at his phone screen, recalibrating to human conversation after millennia of bacterial watching. "Did he?"
"No. He just redefined 'problem' until his equations looked elegant." A pause. "You sound strange. Are you sick?"
"Tired." True enough. The Engine's bargain let him observe without cost, but presence had its own weight. He felt stretched, as if part of him remained threaded through Aethon's timeline even when he surfaced. "What did Kovacs actually solve?"
"Nothing. He proved the cosmological constant is precisely what it needs to be for matter to clump instead of dissipate. But he can't explain *why* it's that value instead of any other. He just pointed at it and said 'look how convenient.'"
"Anthropic principle," Ethan said. "We're here to notice it because it let us be here."
"Circular reasoning dressed up as physics." Maya's skepticism came through sharp and clear. "But everyone nodded like he'd discovered something profound. You would've eviscerated him."
Ethan thought of Aethon's constants, which he hadn't chosen but inherited. Abel had set them. And someone—something—had set Abel's universe to permit both Abel and Engines to exist. Turtles all the way down, each level selecting for conditions that permitted the next.
"Maybe Kovacs is right," he said slowly. "Maybe the only explanation for fine-tuning is that we're the outcome asking about the process."
Silence on the line. Then: "That's not like you. You've always wanted deeper answers."
"Deeper might just be more turtles."
"Ethan—"
"I have to go." He ended the call before she could press further.
---
On Aethon, the stalemate broke.
Not through intervention. Through mutation. A single stromatolite colony on the eastern edge developed a genetic variation that let it metabolize the rival's toxins as nutrients. Within eight thousand years it had overrun the dead zone and absorbed the western colony entirely, incorporating their genetic diversity into its own.
Innovation born from constraint. Success from patient waiting.
Ethan watched the mega-colony spread across the shallow seas, more complex now for having survived its trial. More resilient for having failed first.
The Engine's warmth pulsed against his palm like approval.
Or perhaps just acknowledgment: he had learned to watch properly.