The Invincible Full-Moon System - Chapter 20 Pawn Vampire

In a future timeline, the earth was visited by a species known as the Slarkovs.
Having lost their home planet and in search of a new one, earth was the next habitable planet for them.

Humans and Slarkovs made a deal with each other in return for the Slarkovs living on earth.
The Slarkovs traded their technology and knowledge for a new home.
They were similar to humans except for some of them who had slight differences so fitting into the society wasn't a problem.
Over the years Slarkovs and humans began to mate with one another and reproduce offsprings.
This in turn created a new species known as the mixed-blood.
Centuries later mixedbloods could tap into their bloodline and perform unimaginable feats.

Gustav born into an age where bloodline determines everything, struggles to fit with a useless bloodline.
His bloodline only grants him the ability to change his hair color, destroying his hopes and dreams for a great future.
His fate is turned around when an unexpected situation leads to him finding a system that grants him the power to unlock and upgrade bloodlines by completing quests but he's baffled by two quests with a five-year deadline. Success will grant him unimaginable rewards...
But only one thing awaits him if he fails... Death!

Follow Gustav on his interesting journey filled with unprecedented adventures, danger and death, maybe?

As a successful villainous BOSS, in addition to having ideas and aspirations, one must also keep in mind three points:First, grow sneakily, don't act rashly (once a villain acts rashly, they basically won't survive past three chapters).Second, you're not a good person, so be ruthless (becoming more evil will make you three times stronger, while redemption weakens you by seven times).Third, remember the two points above. The moment you forget them, your end is probably on its way.

Xue Xi is forced to fall in love at first sight with this dangerous man on their first meeting. With death being the only other option, she makes the first move:

In her past life, Lu Zhaozhao placed her trust in the wrong people, inadvertently causing the death of the man who deeply loved her.Reborn on the first day she met him, Lu Zhaozhao decisively dragged Song Si Nian to register their marriage. As she busied herself with dealing retribution and slapping faces, she had only one principle regarding her husband, who suffered from emotional expression disorder: to love him.What Lu Zhaozhao did not know was that she was Song Si Nian's only light. His illness made him paranoid and obsessive, yet he dared not reveal his true self to her.But the truth cannot remain hidden forever. When everything about him was laid bare before her, Song Si Nian held her tightly, tears reddening his eyes, and with a timid voice asked while buried in her neck, “Zhaozhao, do you not want me anymore?”