DS9 Season 4 Episode 3 The Visitor

Plot

The elderly Jake Sisko (Tony Todd) is visited by Melanie (Rachel Robinson), an aspiring writer, who is curious to learn why Jake gave up writing. Jake tells her his story, revealed as flashbacks in the episode.
When Jake was eighteen, his father Captain Benjamin Sisko took him on the USS Defiant to observe an inversion of the Bajoran Wormhole. The inversion causes a malfunction in the Defiant's warp drive; a bolt of energy strikes Benjamin, causing him to vanish into subspace. Believing him dead, Jake and the crew of Deep Space Nine mourn him; but a few months later, Jake catches sight of his father for a brief moment. A year after the incident, Benjamin appears again, but the crew is unable to return him to the normal flow of time.
When the Klingon Empire assumes control of Deep Space Nine, Jake returns to Earth. He eventually achieves success as an author, marries and settles down. When his father appears again, Jake introduces him to his wife and shows him the books he's published. He apologizes for moving on with his life instead of attempting to save his father, but Benjamin is proud of his son's accomplishments. When Benjamin disappears again, Jake decides to help him; he returns to school to study subspace mechanics, abandoning his writing career and marriage.
Decades later, the wormhole is to undergo another inversion, and Jake attempts to recreate the accident on the Defiant. The attempt briefly sends him into subspace with his father. During this "visit", Benjamin is disappointed that Jake has abandoned his writing and marriage in order to save him, and begs him to return to his true passions and live out his life for his own sake. Jake returns without his father and tries to determine what went wrong with the rescue attempt. But eventually he honors his father's request to rebuild his life by returning to writing.
On the night of Melanie's visit, Jake knows his father will appear again. He has injected himself with a lethal hypospray dose, believing that, by dying when his father is present, Jake will allow him to return to a time before the warp core incident. The next morning, Benjamin appears as expected, and Jake tells him that his death will give them both a "second chance". Jake dies in his father's arms; Benjamin finds himself back on the Defiant, and dodges the energy discharge. Confused, young Jake asks what happened. Benjamin tearfully responds, "I guess we were just lucky this time."