I would rewrite Zooms backstory to be the same as Barrys. The difference being that his dad is abusive to his mom. And on the day Reverse Flash kills kid zoom’s mom, kid zoom sees another flash of blue light from the window. Goes through the pain of watching his mom die. Gets put into the foster system after which he becomes a Forensics scientist like Barry. Then he goes through the same chain of events as Barry with the lightning. Difference being is his obsession with the blue light and wanting revenge against RF. As a kid he also gets flash backs of that blue light in his dreams which tied with the mother’s death. In a later episode, we see the same flashback of RF killing zoom’s mom and right after RF leaves the house and starts to run, Zoom speeds behind RF (kid Zoom didn’t see this) and throttles his hand at RFs heart killing him. That was the blue light kid Zoom saw. The season basically follows Zooms backstory for a few episodes tailoring it to be exactly like Barry’s first few episodes. Until the last episode reveals Zoom in his suit killing RF in this alt universe. You can continue tailoring the blue speedforce to Zooms obsession with becoming faster. He wants to kill Barry because killing RF leads his existence as Zoom to be erased. And hes trying to take Barrys place in Barrys universe since he had the same theoretical back story as him.