Marvel: I'm a Symbiote - Chapter 1 Prologue

Xiao Yu, who was a student from modern Earth, accidentally transports to another world and becomes the lord of a territory. Facing an unfavorable situation, he vows to take back his family business, build his new territory, kill all of those who covet his wealth, and dominate the world!

- Description from Novelupdates

Betrayed and butchered by his treacherous best friend, Carlo's soul was consumed by an insatiable thirst for vengeance. Reincarnated into the body of Eduardo, a lowly servant, he vowed to dismantle the ruthless Mafia empire of Marcello Diabolo, the monster who orchestrated his brutal demise.But plans went awry upon meeting Marcello.“You're mine, Eduardo. Why don't you spread your legs for me”Eduardo's resolve wavered as Marcello's seductive pull intensified.“Run, and I'll catch you. You'll never escape my bed” Marcello warned.“I need you inside me, not once, not twice, do it until I break”Torn between revenge and desire, Eduardo's secret threatened to expose him. Would Marcello's obsession endure, or would Eduardo succumb to his enemy's passion?Will Eduardo's quest for vengeance consume him, or will Marcello's fiery passion reduce his resolve to ashes?

In a land where no magic is present. A land where the strong make the rules and the weak have to obey. A land filled with alluring treasures and beauty, yet also filled with unforeseen danger. Three years ago, Xiao Yan, who had shown talents none had seen in decades, suddenly lost everything. His powers, his reputation, and his promise to his mother. What sorcery has caused him to lose all of his powers? And why has his fiancee suddenly shown up?

I was a genius in the Earthen Plane.