Sleeping With My Step Daddy - Chapter 10: "One More Time"

In this world, orphans or just anyone without any hope for this world can apply to become a “walking target”. Their sole purpose is to be a practicing dummy for the students of the sect who train to become “Demon Hunters”. These students need “walking targets” to test their training on living, walking beings of flesh and blood.
In exchange, they will be provided with food & shelter.
Their existence value is lower than a slave, but if they manage to survive a few years they can receive a life long pension.

Xiao Han is such a “walking target”. One time he witnessed a powerful Demon Hunter disposing a demon. When the demon died, a fragment of the demon that managed to escape entered Xiao Han’s heart. No one saw that, and even Xiao Han himself only felt some discomfort for an instant.

But that thing in his heart soon gave Xiao Han visions, and the first one is of a cultivation method which allows Xiao Han to absorb damage to enhance his body. A perfect cultivation method for a “walking target”.

- Description from Novelupdates

“VILLIAN!? Is that what you call me? Do you know what I have been through?

FATE dealt me this hand, and I'll find peace in it. Even if I have to end the world, I'll sit a king on its ruins.

I'm not a good guy. I won't even pretend that I am. But then again, who in this world can truly claim that title?

At least I know my heart. What about yours?”

.....

Chiron lived an unfortunate life, but his problems only got started when he was reincarnated in his dangerous Hit novel.

Behold, a lesson to all authors... MC's have it difficult too.

When the game reappeared in reality, the world went crazy.

Shang Yinhe originally thought he was just playing games, until he horribly discovered: All the games he has played are reproduced in the real world!

The world turned to a strange trajectory.

Expert: There must be a mastermind behind the earth’s change!

Shang Yinhe: That’s me.

Crowd: The brave man who saves the world has a beautiful face!

Shang Yinhe: That’s me.

Earth: Thanks to the Guardian Alliance for protecting me.

Shang Yinhe: That’s me too. #It’s me, it’s me, it’s me#

- Description from Novelupdates

Synopsis below:How did the Avatar universe change when a transmigrant appeared in an unknown village, long before the canonical events? And how are the two islands Kyoshi Island and Uzushiogakure no Sato (A village hidden in the maelstrom)?---Tags: AU, Before-canon, Post-canon, Violence, Death of major characters, Transmigration, Harem, Children, Incest, Romantic. Foul language.