The Immune System of History

They didn't invent time travel to save the world.

They invented it because Miriam hated loose ends.

The team was small and accidental: Miriam, a systems theorist who treated paradoxes like lint on a sweater; Raj, a hardware engineer who built impossible things by assuming they were already built; and Ellis, a historian whose job was to say "please don't" and then document what happened anyway.

When the machine worked—really worked—there was a long, quiet pause.

"So," Raj said. "We all know the rule."

Ellis sighed. "No Hitler."

Miriam nodded. "Naturally."

Naturally, they went back to 1930.

The plan was simple in the way only bad plans are. Eliminate Hitler before he became Hitler. No speeches, no mustache, no genocide, no paradoxes they couldn't mop up later.

The moment they arrived, the machine hiccupped.

Not exploded. Not failed.

It hesitated.

The world shimmered, like reality was refreshing its browser tab.

Ellis frowned. "I'm getting... duplication events."

"What kind?" Raj asked.

"The conceptual kind."

They found Hitler in a beer hall, mid-rant, pre-infamy. Miriam raised the device—compact, elegant, humming with borrowed futures—and froze.

The machine refused to activate.

On its interface, a message appeared:

CAUSALITY ERROR: MOTIVATION NOT FOUND

"What does that mean?" Raj asked.

Miriam scrolled. "It says... our reason for building the machine no longer exists."

Ellis blinked. "But we're standing right here."

The air rippled again. A second Miriam appeared, then a third—each slightly different. One had glasses. One looked hungover. One was crying.

They all spoke at once.

"If Hitler dies—" "—we never build the machine—" "—so we can't be here—" "—so he doesn't die—"

The timeline tried to reconcile this by improvising.

Suddenly, Hitler slipped on a spilled beer and knocked himself unconscious.

The duplicates vanished.

Raj stared. "Did history just slap him?"

Ellis checked his notes. "Yes. And also promoted him. Somehow."

Over the next hour, every attempt to interfere caused reality to course-correct in increasingly absurd ways. A misfired shot became a dramatic scar that made Hitler more charismatic. A sabotaged speech turned into a legendary silent glare. Even accidental inaction seemed to elevate him.

"Causality is defending itself," Miriam said. "Like an immune system."

"So what do we do?" Raj asked. "If killing him breaks the reason we're here, and not killing him keeps him alive—"

Ellis snapped his fingers. "Change the reason."

They looked at him.

"We didn't build the machine to kill Hitler," Ellis continued. "We built it because we believed time travel was possible, and someone else had already used it."

Miriam's eyes widened. "A bootstrap."

They rewired the machine in the alley behind the beer hall, not to kill anyone, but to leave evidence: schematics, equations, a journal signed by people who technically didn't exist yet.

They sent it forward.

The world stabilized. The shimmering stopped.

Hitler finished his rant to polite applause and faded back into obscurity. No dramatic end. No martyrdom. Just... history taking a quieter path.

Back in the present, the team stood in their lab, staring at a dusty notebook on the table.

Ellis opened it. Inside were Miriam's equations, Raj's diagrams, and a final note:

You built this because you already did.

Raj laughed softly. "That feels illegal."

Miriam smiled. "Causality hates loose ends."

Somewhere, deep in the timeline, history exhaled—and let them keep the machine.

Epilogue

Years later, the machine sat unplugged in the corner of the lab, draped in a tarp like an awkward promise. No one suggested turning it back on.

Miriam taught causality as a practical discipline—less what happens if and more what refuses to happen. Her students learned quickly that time wasn't fragile; it was stubborn.

Raj moved on to safer impossibilities. Fusion that worked on Tuesdays. Materials that forgot how to break. He never solved a problem without first asking what the universe would tolerate.

Ellis finished his book. It was banned in three countries, ignored in most others, and footnoted exactly once by a graduate student who suspected the truth and wisely stopped digging.

History, as recorded, showed nothing unusual. No assassins. No visitors. No miracles. Just a series of small, unremarkable events that somehow avoided catastrophe.

And once—only once—Ellis swore he saw something odd in an old photograph from the 1930s. A beer hall. A crowd. A man mid-rant.

In the back, near the door, a blurred shape that looked like a tarp-covered machine.

Ellis closed the book.

Some loops, he decided, preferred to stay loose.