AU: What if Doom Slayer (from Doom: Eternal - after Ancient Gods 1/2), was a Saiyan? How will one change of a person at the very beginning of the story will ripple throughout the DBZ universe's timeline?

And so they watched as the massive burning ball of energy drew closer to the planet. Every Saiyan accepted their fates as they closed their eyes, waiting for death to take them. Until… he came.

The deamons begin invading the planet earth through unknown sources and start giving everyone a lot of trouble. The Z fighters and doomguy team together to take on the threat that has risen.