Blood's Run Stale (Voltron:LD Fanfic Klance)

Daibazaal Labs was experimenting on omegas when one brain experiment goes terribly wrong. It gave the omegas unnatural strength that allowed them to break out of their bindings and attack the alpha and beta scientists. It also affected their saliva so that when they bit someone, it transferred the experiment affects onto the bitten. A fire then broke out at the labs, allowing most of the zombies to escape. That's how the outbreak began and spread like wildfire.

Two years later, Keith was a loner during the apocalypse. When he gets injured and ducks into a safe nook, he is found by an old friend and his group. Keith must remember what it is like to be with other people, especially after being a lone omega for two years.

(Cross post with AO3)