Global Demonization

The purple sun rises in the sky, monsters and monsters come to the world, and there are many dangers in the dark night. After Yu Sha became a night watchman guarding the darkness for mankind, why did he choose to betray the organization and set up his own faction? What was it like for his former comrades to become enemies? PS: The first monster image of the protagonist is the alien from the Alien universe, the second is Venom from the Marvel universe, and the third is tentatively decided.