I Transmigrated Into a Book With a System, So Why Am I the Only Cannon Fodder?

Chi Sui accidentally transmigrates into a book, and not just any book: one he'd recently read part of. It's a story about two powerful men, an agent and an assistant, and he is merely a cannon-fodder character working under the protagonist.

Chi Sui: Other people transmigrate into books, get a System, and reach the pinnacle of life. Why am I the only one who's cannon fodder with the exact same setup?

System: Don't ask. It's your problem.

To avoid his cannon-fodder ending and return to his own world, Chi Sui can only diligently complete the System's missions.

What he doesn't expect is that, while he's helping the protagonists get together, someone else has been keeping an eye on him all along.