This is 18+ Finished. Kiribaku, or should I even say KiriBaku Eijiro x Katsuki.

The Black Lion is the head of Voltron, the most powerful weapon in existence, the symbol of freedom and peace across the universe. Its pilot seat is like a throne-a throne that belongs to Keith. James has other ideas. Or, James sits in the Black Lion's pilot seat while Keith worships him.

Mermaid!ErenxPirate!Levi eren is a mermaid in a migrating pod with his family, but when pirates come to get one for research, Eren is the one who get caught!