A Perfect Scumbag's Guide [Quick Transmigration]

After S-rank superpowered ability user Wei Hengzhou died, he signed a contract with the System. His mission was to travel to different worlds and resolve the resentments of the cannon-fodder male leads, allowing them to be reincarnated successfully. These included, but were not limited to: A genius biochemist who developed a serum conferring immunity to the zombie virus, only to have his work stolen by the student and assistant he had always cared for, then be thrown into a horde of zombies and bitten to death; An all-around ace performer in the entertainment industry who protected a silly beauty every step of the way, only to be used as a stepping stone in his career, smeared with false rumors, terminated by his company, saddled with an enormous breach-of-contract penalty, and driven to suicide in despair; A thousand-year-old tree demon who protected the ancestral home of its benefactor's family for generations, only to be betrayed by a descendant who became head of the family, have its inner core dug out by a celestial master sent by the court, and finally burn to death in a raging fire; The Federation's top sentinel, who earned countless honors for the Federation, only to be betrayed by his childhood friend and guide, falsely accused of being an imperial spy, imprisoned unjustly, and die in despair... System: Your mission is to fulfill these people's final wishes, turn the plot around, and make a triumphant comeback. It would be even better if you could also gather the protagonists' affection along the way. Wei Hengzhou: Oh... Got it. Later... System: I told you to fulfill the cannon fodder's wishes, not to become the big boss and crush everyone! And hey, let go of that male lead! Quick transmigration with a male protagonist, strong characters, love and hate tangled together, and one-on-one pairings in each arc. The cannon-fodder male lead romances the original male lead. (The protagonist is naturally black-hearted and a bit crazy, but has a chaotic good alignment.) Note: In some worlds, the bottom has prior sexual experience but is inexperienced with the top. Theme: Keep your cool, and you can turn the tables even in adversity