I remember writing stories, or actually writing outlines of stories, of space adventures. Some were fan fiction stories based on Star Trek. Some were sci-fi adventures of brothers off in an interstellar travel. After the 2nd Star Wars movie, I even wrote what I thought should be the 3rd movie in the trilogy.
I was in the Navy, onboard a nuclear submarine at the time. Not much to do except stretch your imagination. I also wrote several poems/songs during that time. Prose about men and women falling in love, breaking up, coming back. It was the product of seeing what was happening to my shipmates, and myself.
I recall one of my first stories was about two brothers off on a sub-light flight to another star system and suffering damage along the way. One of them was severely hurt and the surviving brother transferred his dying brother’s consciousness into a robot. It surprised me many years later to see something similar done in an anime series (Full Metal Alchemist). Don’t think they stole my idea, but it was kind of cool to see someone else had also came up with the idea.