Savitar's origin story is quite an interesting one. He was a time remnant of Barry Allen, which basically means he was a leftover part of Barry from a time - travel event. This remnant was then left to fend for itself in the chaos of the time - stream. Over time, he grew resentful towards Barry for abandoning him. His origin story is marked by this sense of abandonment and his subsequent journey to gain power. He developed a following, who worshipped him as a speed - god. He used his knowledge of the speed - force and his own dark desires to create a terrifying persona. His origin story is deeply intertwined with the concepts of time, power, and revenge in the Flash universe.
Savitar's story begins with a twist in the time continuum. Due to Barry's actions, a time remnant was created that transformed into Savitar, driven by anger and a desire to shape the future to his will.
Savitar started as a time remnant from Barry Allen. After being left adrift in the time - stream, he turned bad. His origin is rooted in that abandonment and his need for power.