Serenade - Chapter 30: Ten Levels of Anger

What happens when a scientist from a futuristic world reincarnates in a World of Magic and Knights? An awesome MC is what happens! A scientist’s goal is to explore the secrets of the universe, and this is exactly what Leylin sets out to do when he is reincarnated. Dark, cold and calculating, he makes use of all his resources as he sets off on his adventures to meet his goal. Face? Who needs that… Hmmm… that guy seems too powerful for me to take on now… I better keep a low profile for now. You want me to help you? Sure… but what benefit can I get out of it? Nothing? Bye. Hmmm… that guy looks like he might cause me problems in the future. Should I let him off for now and let him grow into someone that can threaten me….. Nahhh. *kill*-

Alternative: Leylin is transported from an advanced technological era into a medieval world— except there’s magic. Equipped with “only” his quick wits and an A.I. chip fused to his soul, he sets out to become the most powerful magus the world has ever known. In a land divided into the Light and Dark Magi, the weak can either be cattle or disposable slaves. Only the strong can determine their lives, and only they have the luxury for virtue. Yet strength is only a tool for Leylin, like any other. His goal, in the end, is his own.

Mason was a mercenary, until the day he died on a mission after being betrayed by his unit.

Wang Cheng: Boss Chu, I think my mom will not agree two hundred percent with our affair, so I have a once-and-for-all proposal, do you want to hear it?

Chu Yifeng: Let’s hear it.

Wang Cheng: It’s very simple, why don’t we break up and not worry about anything?

Chu Yifeng: What you said is quite reasonable, but we can discuss this matter further in the bedroom.

Wang Cheng: …I’m just kidding. Look at my sincere face. How could I break up with you?

Chu Yifeng: It’s too late.

- Description from Novelupdates

Falling in love with my imposter sister's fiance wasn't the plan. After finding out that she was exchanged at birth and was the real daughter of the Moore family, Eliana was expecting a turn in her life, but nothing changed except that she lived in a big house and could now eat good food. Her parents still ignored her and everything good was first given to Amber, their imposter daughter.She was twelve when she met him, when he saved her from drowning, and when she found out that he already had a betrothed. It was already known that the eldest son of the Sanders family was betrothed to the eldest daughter of the Moore family since birth. She knew this, and it was only natural that she accepted this, but the more they crossed paths, the more she wanted him and the more she wanted more for herself. Eliana was ready to do anything to achieve all her dark desires, even if it made her a villain.After all, there is a saying that goes “Villians are not born, they are made.”