After I Transmigrated as a Good-for-Nothing Dragon Prince, I United the Continent

(Two male leads, protagonist in the seme role, low-magic Western fantasy with powerful martial arts, medieval setting, dragons) I transmigrated into a popular male-lead novel and became a disposable dragon prince whose bloodline is drained by the protagonist at the start. Good news: I got bound to a System. Bad news: I can only grow stronger by getting close to dragonblooded men. To stay alive, I act like a scheming green tea and the one pure white jasmine in the world. But how did all this acting turn into... unifying the continent? (Note: The protagonist isn't very smart and is selfish. He's into men, and he'll do whatever it takes to survive.)