Warhammer: Starting as a Planetary Governor - Chapter 28 - : Conflict

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates

In his old world, Elric had nothing—no powerful family, no elite degree, just relentless hard work and a passion for healing. Dismissed as a third-rate doctor, he shocked the nation by saving a congressman’s life and becoming an overnight celebrity. But just when his career was rising, tragedy struck.Now, Elric opens his eyes in a world unlike any he’s ever known—a land of swords, sorcery, and strange beliefs. Reborn in the countryside of a magical kingdom, where even a common cold is blamed on spirits, he’s the only one who understands how the human body truly works.With no palace, no power, and no one to trust, Elric sets up a humble clinic in a rural village. Armed with science and sarcasm, he treats the sick, challenges ancient traditions, and slowly earns the awe and fear of a world ruled by magic.Mocked as a fraud. Hunted by rival healers. Feared by nobles and mages alike.But this world is about to learn—Even a third-rate doctor can change history.

Zhangsun Zijun and Yi Xichen are the protagonists of the novel “Record of Nine Thousand Vicissitudes.” One is solid and reserved; the other is free-spirited and uninhibited. As fellow disciples under the same master who grew up together, the two have a deep friendship that was strengthened by their numerous life and death adventures together.

However, in a popular yaoi fanfiction, the personalities of these two characters is completely OOC. Zhangsun Zijun turned into an insanely jealous, insatiable s*x addict madly in love with his wife Yi Xichen. Yi Xichen turned into a sweet, delicate little angel. Their daily life was full of kinky bedroom activities…

Suddenly, the Zhangsun Zijun character from the fanfiction was transported into the world of the original novel.

- Description from Novelupdates