Star Trek Voyager: IM Tom Paris

He's sitting in the New Zealand penal colony brig when Kathryn Janeway walks through the door, and he already knows every word she's about to say. The HELM system planted something in him called The Long Way Home Engine - a Ledger containing the complete 70-year route back to Earth, every anomaly, every shortcut, every moment the original Tom Paris stumbled toward home on instinct alone. The catch: every time he deviates from the charted path, the Ledger corrupts - not erases, corrupts - and something from a timeline the show never wrote wakes up in the gap. His Simulation Forge lets him war-game Delta Quadrant threats on the holodeck before they arrive, prototype the Delta Flyer three seasons early, run the crew through battles they haven't lost yet. But the Conn-Officer Pilot Reflex Ladder only unlocks through sim-crashes - muscle memory that costs him something each time. He has the map. He has the pilot's hands. What he doesn't have is a Ledger that stays intact when he saves someone the original timeline let die.