Sui Dynasty: How Did a Scholar Become the Imperial Bodyguard?

[No System + Comedy + Absurdity + Steady Progress] After transmigrating to the Great Sui, he is overheard thinking by Emperor Wen of Sui. [Holy crap, the Great Sui will last 600 years, and Emperor Wen will depose the eldest son in favor of a younger one, picking someone who will bring the empire to ruin.] Emperor Wen of Sui: What? Guang'er will bring the empire to ruin? Then the crown prince's position will remain vacant for now. [The Great Sui will fall in eighteen years. I need to find someone powerful to back me before then.] Emperor Wen of Sui: You think you can run? Aiqing Wu, who do you think should be crown prince? [You're asking me? None of your sons has any promise!]