The Death Particle

Upon the creation of the universe billion years ago, or in this case your verse, the fate of everything was decided when matter outnumbered the antimatter particles during their annihilation. We were wrong. The reason why anti matter was outnumbered was because it decreased. No, it didn't. Two particles condensed and formed something. Something truly mysterious yet magnificent. A particle whose creation may lead to the death of the Cosmos. We call it the Death Particle. Any life form carrying the particle of Death is a threat not only to the world you know, it may destroy the very existence of your universe.