It could be the Time Wraiths. Since Barry is taking on the identity of Savitar, who was a time - aberration, the Time Wraiths might come after him. They would view him as a threat to the proper flow of time and try to eliminate him, making them the main antagonists in this fanfiction scenario.
Yes, there are several. You can check fanfiction websites like Archive of Our Own. Just search for 'Barry is Savitar' and you'll find a variety of stories with different takes on the concept.
Fanfic about Barry Allen and Savitar usually plays with their powers. Barry's super - speed is well - known, and Savitar also has this ability. Writers in fanfic might create scenarios where they race or use their speed in different ways. It could be a showdown of who is faster or how they use their speed to outwit each other.
In some fanfics, Barry might also be shown as having a personal vendetta against Savitar. Maybe Savitar has hurt someone close to Barry, so Barry is not just fighting for the city but also for revenge. This adds more depth to his character in the fanfic.
Barry Allen x Savitar fanfiction often plays with the idea of alternate universes. Writers may create scenarios where they are not enemies but rather allies or even something more. This can lead to interesting character developments. For example, Savitar's time - related powers combined with Barry's speed could be used in unique ways to solve problems or face new threats that were not present in the canon storyline.
One possible scenario could be that Barry Allen is exposed to some dark energy or a time - related anomaly that slowly starts to corrupt his mind and make him turn into Savitar. This could be due to his overuse of the Speed Force, which has unpredictable effects. Maybe he starts to see the world from Savitar's perspective, believing that the only way to 'fix' things is through Savitar's extreme methods.