The story where Eobard Thawne tries to rewrite history to make himself the greatest speedster is a great one. He manipulates events in the past and present, and his battles with Barry are intense. It really showcases his devious nature and his determination to be on top. There are also some great emotional moments when Barry discovers what Thawne has been up to, adding depth to the story.
In this fanfiction, it's possible that a symbiote - influenced villain could be the antagonist. Maybe someone who has bonded with a part of the symbiote and has a thirst for chaos. They might see Flash as an easy target to cause mayhem and draw out Spider - Man. Additionally, the Scorpion could be another antagonist. He might be hired by some shadowy figure to capture Flash in order to lure Spider - Man into a trap. There could also be a group of alien invaders who mistake Flash for someone important and Peter has to save him from their clutches.
Well, perhaps Flash gets into some sort of trouble like being kidnapped by a group of villains who want to use him as a bait to lure Spider - Man (Peter Parker). Peter, using his spidey - senses, tracks Flash down and has to fight off the bad guys to save him. It could also be that Flash accidentally stumbles upon a dangerous experiment and Peter has to save him from the resulting chaos.
Eobard Thawne is from the 25th century. He was a huge fan of the Flash (Barry Allen). However, his obsession turned dark. He managed to replicate the speed - force experiments that gave Barry his powers. Thawne became Reverse - Flash. He traveled back in time to meet his idol, but his actions led to many problems and conflicts, ultimately becoming one of the Flash's greatest enemies.
One key element is his origin from the 25th century. Another is his obsession with the Flash. Also, the replication of the accident that gave Barry Allen his powers is crucial.
Eobard Thawne is the Reverse - Flash. His origin story is quite complex. He was from the 25th century and was a huge fan of the Flash, Barry Allen. He managed to recreate the accident that gave Barry his powers, but it had some unforeseen consequences. This led to him becoming a speedster with a warped sense of time and a vendetta against the Flash.