So This Is the Kind of Immortal Lord You Are

Five hundred years ago, the Demon God Yu Shimu tore a hole in the heavens.

A cataclysmic inferno rained down upon the mortal world. Spiritual energy vanished, all things withered, and the cultivation world suffered devastating losses and rapidly declined. Demons and monsters ran rampant amid the chaos, and the human world sank into a hellish sea of fire.

Five hundred years later, Yan Tingzhou is sent back to that time with a mission: kill the Demon God and save all living beings.

*

The plan for this trip went like this.

He would return to the past and meet the Demon God before he went completely insane. The Demon God would either be impoverished or weather-beaten, so Yan Tingzhou would warm him with love, care for him, and change his heart. First, he'd persuade him to turn back from the wrong path. If that failed, they'd become hopelessly entangled, live and die for each other a hundred times over, and, when the Demon God least expected it, he'd finally stab him. Shunk...

The plan made Yan Tingzhou's head spin and his soul tremble. So when he opened his eyes

He'd! Been! Split! In! Two!

Yan Tingzhou's soul had transmigrated into the Demon God's own body. The two of them stared at each other in his blood-red sea of consciousness, both at a loss for words.

Just as Yan Tingzhou thought he was about to meet his end, the Demon God spoke: "Since you're here, want some lychees?"

*

The Demon God wasn't at all what they'd expected.

In the cultivation world of five hundred years ago, Yu Shimu was the only person born with a Dao body. He'd been exceptionally gifted from childhood, carried the hopes of many, and enjoyed enormous prestige. Wherever he went, people answered his call.

He wasn't twisted at all. In fact, he was universally praised as the number one Immortal Venerable, with the best chance of attaining the Dao and ascending to immortality.

With his original plan in tatters, Yan Tingzhou could only deal with things as they came. Temporarily in control of this body, he carried a bag of lychees Yu Shimu had sent him out to buy and couldn't help wondering:

...This man had been blessed with every advantage and had everything he could want. What on earth could have driven him to throw his life away and turn himself into a Demon God infamous for a hundred years?

*

From the moment Yan Tingzhou appeared inside his body, Yu Shimu knew who he was.

Yan Tingzhou's face in the sea of consciousness was cool and composed, but his tightly pressed lips gave away his nerves. Yu Shimu studied him for a long while, pushed his favorite lychees toward him, and reached a conclusion.

Beautiful.

Beautiful when pretending to be calm, beautiful when acting mature, beautiful when serious and stern. Even his trembling hand was beautiful when he was about to draw his sword and kill him.

He heard Yan Tingzhou ask him, "Why?"

Yu Shimu smiled and answered, "Isn't that what you came here to find out?"

"You're looking at me from five hundred years in the future, where my ending is already set in stone. Why are you still sad?"

Mad criminal top (Yu Shimu) x cool genius bottom (Yan Tingzhou)

*After transmigrating, they share one body and two souls. They'll separate later; they won't stay in one body forever.

*Five hundred years after you died, I finally met you. You finally got to wait for me.

*He is my present-day body; I am the soul in his dreams.

Theme: I know you have immortal bones, untouched by heat or cold. A thousand years apart, meeting you feels like the very next day