The Emperor Guards the Nation's Gates

Qi Mei transmigrated into the body of a crown prince in a fallen dynasty. Before the rebels breached the capital, the crown prince's emperor father killed him as he took his own life. Qi Mei had struggled to survive through years of the apocalypse. All he wanted was enough to eat and a chance to stay alive. He didn't care in the slightest whether the dynasty fell. He was focused on figuring out how to latch onto the rebel leader's powerful coattails, so he could secure himself a meal ticket and a life free from worry. But after the rebel leader, Prince Qin Wei Zheng, arrived in the capital, he generously extended his leg. "Come cling to it." Qi Mei happily did. Wei Zheng: "Can you warm a bed?" Qi Mei: "...Yes." An emperor seme who nearly lost his country, but ends up keeping it and being thrust onto the throne by the rebel leader x a powerful, frail regent shou. 1v1, happy ending. Neither the seme nor the shou is a good person.