Broken Bodies, Broken Hearts
When Hanzo enlists in the army to fight the war against the omnics, Jesse can't bring himself to miss out. Building limbs for soldiers and trying his best to contribute to the war at hand, he finds himself being sent to the base Hanzo inhabited. After he gets instructed to create limbs, he finally gets to meet one of the victims. Heartbroken, he fights to help him walk again.
(ADDITIONAL NOTE: Omnics are the opposition in this, though everyone is human. Overwatch is kinda like a codename for whichever country Jesse and co. are fighting for, like Omnic would be a codename for their opposition.)