Well, in a Commander Rex time travel fanfic, he could go back to crucial battles and change the outcome. Maybe he'd prevent some of his comrades from dying. For example, he could go back to the Clone Wars and use his future knowledge to outwit the Separatists more effectively. He might also meet his younger self and give some valuable advice, like how to better handle difficult situations or make wiser decisions in the heat of battle.
Rex's character might develop a sense of mystery. People around him would be curious about his time - traveling experiences. He might not be able to fully explain all the things he's seen and done. This could make him seem more aloof or even a bit of an enigma. But at the same time, he'd still be the same loyal and brave Rex deep down, just with a new layer of complexity added to his personality.
Rex found himself in a strange, swirling vortex of light. Suddenly, he was thrust back in time to the prehistoric era. He stared in awe at the dinosaurs roaming freely. Rex knew he had to be careful not to disrupt the natural order. He hid behind a large boulder as a T - Rex passed by, its massive feet shaking the ground. Rex started to wonder how he could find a way back to his own time while also making the most of this once - in - a - lifetime opportunity to witness history up close.
One common theme is self - discovery. When Rex travels through time, he often has to re - evaluate who he is and what his purpose is. Another theme is changing the past or future. Since he has knowledge from different times, he may try to alter events.
One great Rex Clone Wars time travel fanfiction is 'Rex's Time - Hopping Adventure'. It has Rex traveling back to key moments in the Clone Wars and changing small things that have big impacts later. It's really exciting to see how he uses his knowledge of future events.
One possible scenario in such a fanfiction could be that the Anbu Commander travels back in time to prevent a major tragedy in the Naruto world. Maybe he goes back to stop the Uchiha massacre. He could use his knowledge of future events and his Anbu skills to change the course of history.
Perhaps Rex travels to a time where dinosaurs and humans co - exist. He has to figure out how this is possible and if it's a threat to the future. Or he could go back to the time of the Renaissance and become an apprentice to a famous artist, using his modern perspective to influence the art world in ways that have a ripple effect through time.
A really interesting piece is 'Rex and the Time Anomaly'. This one has Rex accidentally traveling to a time far in the future of the Star Wars timeline. He has to figure out how to get back while also dealing with the strange new technologies and cultures he encounters. It's a fascinating exploration of how Rex would adapt to such a different environment.
One more interesting plot is when Rex travels back to the very beginning of the Clone Wars with the knowledge of how it all ends. He tries to prevent the start of the war itself or at least change the way it unfolds. This gives the author a chance to rewrite the entire Clone Wars saga from Rex's perspective. In the fanfic 'Rex: Rewriting the Clone Wars', he tries to expose the Sith plot much earlier, which sets off a chain of events that are completely different from the original Clone Wars.
Another element is the Anbu Commander sharing future knowledge. He might tell the younger Kakashi about Obito's survival, which would change a lot of things in the story. This would create a whole new set of interactions and story developments. He could also share knowledge about new jutsu or threats that are coming in the future, which would allow the ninja of that time to better prepare.