I was recently reminded of sci-fi short story which I read quite some time ago (several decades, possibly) which was entirely a monologue.
The narrator is talking to two professors and it's revealed that they stole something technical from him. Either the secret to time travel directly or something that could be extended into time travel. During the story it becomes clear that the narrator has learned to manipulate time travel to such an extent that he was able to alter events so that he could not only win over his rivals, but in such a way that they'd be psychologically identical, so he could gloat over their downfall.
The resolution, according to my memory, was the narrator had taken over the religious order the rivals had created, and done so in such a way that the rivals were now seen as heretics and the story ends with the populace showing up with torches and pitchforks to take down the rivals.