Au where Ben is a sailor on a ship led by his mother, and Hux is the mermaid who wished to lure victims down below.

Ben is too reckless and confident to heed his mother's advice, and stays on deck during night time despite her warnings. And then he hears something. At first, he thinks it's the wind, until he realizes it's a song. Not just any song, but the most beautiful one he has ever heard.

And it is sung by the most beautiful man he has ever seen. It doesn't matter if he has a large, back tail, or too sharp teeth in a predatory smile, Ben knows he will do anything this man asks as long as he can listen to this song forever.

Something Hux is more than willing to promise just before he drags Ben under the water.

Bonus:
+ Hux keeps Ben in an underwater cave, always in thrall thanks to his song.
++ Leia tried saving her son, to no avail.
+++ Mermaid/Human sex. You decide how it works, anon!