Star Trek: The Metamorphoses

 In 2119, Zephram Cochrane opens the first warp five complex, his last public appearance before heading off for a retirement that would shortly end in the last time history hears from him until Kirk discovers Cochrane alive in 2267.  He's been presumed dead after transmissions cease from his solo J-class starship journeys launched from Alpha Centauri, where he'd been living in his later years.  

Here's where things become a little complicated.  It'd be easy to take Cochrane, and the Companion, at their word, that the man Kirk meets is in fact Zephram Cochrane.  But the truth is far stranger, as it tends to be.

In 2161, Charles "Trip" Tucker III dies saving Jonathan Archer from a band of space pirates.  Everyone knows this.  Everyone except the people who like to claim his death was faked and he in fact became an agent for Section 31, becoming integral to their efforts during the Romulan War.  Which is of course sheer nonsense.

He didn't fake his death.  He died.  But the Companion brought him back.

By that year, Cochrane had been living with the Companion for nearly forties years, and by Kirk's perspective still had nearly a hundred years yet together unquestioned.  This is a lot of time.  The Cochrane Kirk meets is youthful, younger, apparently, than even the Cochrane who conducts the first successful warp flight in human history in 2063, when he was in his thirties but looked like he was in his forties at least, due to the rigors of life post-WWIII, where he scrapped for a living in Bozeman, Montana.  The Cochrane Kirk meets, then, is in his early twenties, still arrogant enough, when he was that age, to believe anything is possible, not yet the cynical man who made history, who made Earth's first official contact with Vulcans.

The Cochrane in 2161 was, chronologically, already over a hundred, having accomplished great things and then been deposited in an out-of-the-way planet where he could dwell on the youthful ideals his life had brought him back to, but with all the experience that led him there, his every need met by the Companion.  He had ceased questioning the arrangement years earlier, and yet...

The Companion knew.  Even if Cochrane himself didn't, things needed to change.  Cochrane itched ceaselessly for some new challenge.  For all he knew, humanity could still very much benefit from his talents.  He was cut off from the outside world, had no clue Starfleet existed, much less the state of human/Vulcan affairs.  The Vulcans he knew had made humanity bitter, and Vulcans themselves constantly having to mask annoyance, a relationship that jarred with Cochrane's hopeful outlook.

So the Companion sought someone who might alleviate Cochrane's distress.  That someone had just died, but such distinctions were trivial to the Companion, who brought Tucker back to life, and introduced him to Zephram Cochrane.  The Cochrane Tucker met looked every bit his age, looked tired, looked old, but still vital, in the mind.  Cochrane bombarded him with his many questions.  He listened, astonished, at news of the Xindi conflict, the Temporal Cold War, the budding Federation, how far Cochrane's pupil Henry Archer had pushed warp theory, and his son Jonathan, humanity's relationships among the interstellar community.  

And he confessed that he had his doubts about life with the Companion.  Tucker listened.  Tucker had spent a colorful Starfleet career confronting all manner of outlandish situations.  To him, life with the Companion almost seemed...natural.  He understood that he had died, and was happy about the circumstances in which it had happened.  He had no interest in changing what his friends thought had become of him, of resuming an old life that had had plenty of unwelcome complications.

So he proposed something to Cochrane, and then to the Companion.  He would take Cochrane's place.

Cochrane found himself relieved.  He would get what he wanted, and so would the Companion, and so would Tucker.  Of course it meant his death, but he was ready.  He was more than ready.  And so that's exactly what happened.  And for the next hundred years, Tucker lived with the Companion, and he lost himself, happily, in the process.

When Kirk came upon this planet, he found Tucker and the Companion, and all the clues suggested Zephram Cochrane.  Tucker was, of course, listed as having died quite conclusively.  This was an age in which so much information was available, it was impossible, even with all of it easily at hand, for anyone to know enough to tell the difference in such circumstances.  Like any age, really.  So no one questioned if Zephram Cochrane didn't look like Cochrane, and actually looked a great deal like, well, Charles "Trip" Tucker III.  And Tucker was happy to play the role.  And he was happy, one last time, to play out a screwed-up situation, and then live on with the Companion, for the foreseeable future...

Kirk solved one mystery.  He left behind a much bigger one, but one that had already happily resolved itself.

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Do yourself a favor and rewatch the classic Star Trek episode "Metamorphosis" and tell me that the actor playing Cochrane, in hindsight, doesn't look and sound remarkably like Connor Trinneer, who played Tucker in Enterprise.  Watching it myself, recently, it instantly brought the idea of this story to mind.