Sweet Hatred - Chapter 12: Firefly

It’s a affair between a loyal dog servant and his master.

- Description from Novelupdates

When an S-class elite assassin-raised captain of a special ops suicide squad comes home from a high-stakes Africa mission, he finds himself offered something that could potentially set him up for life- a curious assignment that he could use to finally exit his days of war and slaughter.

Then placed into a high-school setting, Lin Yi is tasked by the chairman of a top-tier multi-billion company with bodyguard duty for non-other than his own daughter, a certain little Miss of said high-school.

His enemies, once ranging from drug lords, mafia bosses, political figures, and national leaders, are soon replaced with spoiled kids who happen to have rich papas and mamas, and Lin Yi finds his intense expertise and high-threat skillset misused, and very underwhelmed…

But he does get a harem cast as diverse as his old enemies, so Lin Yi decides that, for the sake of messing around with girls as an invincible entity in a down-leveled environment, leaving his bloody and death-filled war days behind is something he’d definitely want to strive for.

- Description from Novelupdates

Forced to be married, only to find out he's the one she loves the most.

Su Anan was forced by his father to marry a rumored ruthless CEO. She was resentful and scared because she didn't know what this cold man would do to her. But as they spent more and more time with each other after marriage, she found out that he was a gentle and considerate husband, so she naturally fell in love with him.

Her half-sister often bullied her, he came to help her revenge. Her biased father often beat her, he ruined her father's career with anger. Relying on his love, Su Anan revenged thousands of times to those who bullied her. After all, her CEO was the most powerful person in the city, and no one could bully her anymore.