trapped sea dragon

you were in the underwater city where you normally live, you had no parents, so he was the one who took care of you because he was the older brother, even more so because you had a slight disability (you can choose).

And in one day, you could see a little bit of him just disappearing.
the humans captured him with thick, strong fishing ropes and took him to a kind of "base" on a coastal beach that no one in the human region seemed to know about, he was tied up with restraints and belts all over their bodies on the very cold metal floor, near the boat that was tied by a rope nearby. It had been there for hours...