My Father is a Hero, My Mother is a Spirit, the Daughter (Me) is a Reincarnator. - Chapter 9: The Appearance of Little Brother

She was drugged by her ex-boyfriend and had her first night with a mysterious man.

The end of the world is coming, the world has undergone great changes, and everything has changed. Plants, animals, and even insects, as long as there are living things, have mutated.
Become more powerful, and even evolved supernatural abilities, such as chickens and ducks that can fly to the sky, such as cats and dogs that can breathe fire.
But only humans, without any obvious changes, seem to have fallen from the top of the food chain to the bottom of the food chain overnight.
Any creature that can open its mouth to eat can treat humans as food.
But fortunately, this world has not completely killed humans. Gradually, humans discovered that they had the ability to cultivate compatibility with other creatures.
As long as it has a high degree of compatibility with some powerful mutant creatures, it can be used for its own use to achieve the purpose of protecting itself.
Fang He is a person who is very compatible with mutant animals, but it is also because of his ability that he has changed from the strongest to the stupidest.
Fang He, who was reborn, said, “Hmph, this time…”

- Description from novelbuddy

Villain System: Activated> Alignment: Chaotic EvilObjective: Obey the plot, serve the empire, die like a good villain.Yeah, no thanks.I woke up as Dorian Valen—sadistic noble, arsonist, war criminal, mid-tier villain with a face everyone wants to stab. The story wants me to beg for my life, cough up secrets, and die at sunrise so the hero can get a shiny new power-up. Been there, read that.But I'm not here to follow the script. I'm here to flip the table.I’ll expose the cracks in the empire, dismantle the hero’s halo, weaponize every trope, and corrupt the system that tried to cage me. And if I have to burn the world down to do it?Well… I’ve got the villain system. Might as well make it earn its name.

Mark hatched out of an egg one day, reincarnated as a demon!His body was as strong as iron, instincts capable of noticing a silent fly multiple meters away. Eyesight sharp enough to see the small holes in an enemy’s clothing.Moreover, he also had a system.[Soul Devourer][Eat souls to grow stronger.][Mind-type Demonic Tricks have been derived out of your demonic bloodline!][Heart Input!][Input unsolicited thoughts in an enemy's heart and influence them!]Mark took a deep breath.How can he allow himself to live a mediocre life after being given this second chance?Now, he wanted it all!Women, wealth, power, status, and even eternal life!His ambition was set, his heart was on fire. A demon had been born.