Help! This Human Attendant Is Way Too Charming

My first novel, a shameful relic. Don't read it! Don't read it! 【Two Male Leads + Xuanhuan + Flirting and Falling in Love + A Little Goofy + All-Out Devotion + Winning a Third Prince of the Merfolk as a Husband】 The merfolk are a free, beautiful, and mysterious people. A hundred years ago, other races coveted them and joined forces to invade the South Sea, nearly wiping them out. They were saved by the Sea God, who sacrificed his life to establish a barrier at the entrance to the South Sea that only the ruler of the merfolk could open. From then on, the merfolk were forced to take human legs and live in an underwater city, focusing on cultivation so they could defend themselves in the mortal world. One is a human assassin, the greatest prodigy in swordsmanship in a thousand years. The other is the third prince of the merfolk, a feared solitary star born under an ill omen. The once-great sword prodigy has had his internal energy destroyed and become a cripple. He is forced to enter the South Sea to assassinate the third prince. Everyone knows that the third prince is decisive and ruthless, indifferent and heartless. Yet he falls for a human. Their first meeting and their daily life together make a once-cold heart beat with warmth. As open attacks and hidden daggers keep coming, and more people and things get drawn into the fray, the two discover a destiny they cannot escape. He wants to protect the one with no inner energy, and keep him safe for the rest of his life. Among all the people in this world, you alone are my love.