Why Is the Villain in the Book Acting Differently?

(One-on-one, dual male leads, both pure) Song Xiao was the youngest in his family. After all those years, he was finally about to graduate from university and enter the working world. Just before his senior-year graduation photos, he went to his eldest sister to get the clothes he needed for the shoot. He accidentally tripped over a doll by her door and hit his head on the novel on her desk, A Pact Between Me and the District Chief. When he opened his eyes, a fellow calling itself System 241 said it was going to bind him to a villain redemption plan! “Not interested. Send me back, now! Otherwise, I'll sue you for unlawful confinement. My second sister's a lawyer!” “I'm not imprisoning you. It's just an ordinary... uh, job?” “Oh! I get it. Then I'll sue you for unlawful, unlawful employment!” “Huh?” System 241 was dumbfounded. Why was this different from before? Jiang Chenyuan had been delighted when offered a job! System 241 could only explain itself over and over until Song Xiao finally believed it. But as the missions went on, the plot somehow started going off the rails. Why had the villain become the leader? And why were both the male and female leads listening to him? “Yan Xihua! Why are you walking so fast?” Yan Xihua stopped and turned to look at the slowpoke Song Xiao. “There's a zombie behind you.” “Ah!” Song Xiao shot past Yan Xihua. “Run!” Yan Xihua watched Song Xiao's retreating figure and smiled. “Idiot.”