Cursed as he is playing along the beach with a female childhood friend with a monstrous arm by the pirate king in revenge for his father killing the father of the pirate king.
To stop the curse from spreading he is given a tooth necklace from his father stopping the curse from spreading to the rest of his body. Then on his 18th birthday he is told to gather a pirate crew and seek 12 parts to a map which will lead him to a magical book which he needs to use to banish the Monster Pirate King and his crew to the depths of the underworld and release the boy from his curse.
The necklace holds great interest to the Villain as the boy doesn’t realise that the tooth is a key to the chest that the book is encased in therefore tries his utmost in stealing the necklace from the boy to use the book to summon terrible sea monsters and become king of the seas.
2nd Idea -
A young boy is prophesised as being the one to stop the reawakening of 7 of the most monstrous pirates. The young boy overhears a captain of a pirate ship speak about a map in their possession which leads to 7 mysterious islands not shown on any other map. The boy smuggles himself on the captains ship but is caught and forced to work on the ship. The boy gains the captain's trust through a few battles by showing great courage in protecting his captain. The captain tells the boy that he is sick and will not be able to continue running the ship and tells the boy that he is the pirate boy that is the one to stop a monstrous crew from awakening the 7 islands which will release 7 monstrous pirate kings. The boy is given a magical cutlass by the captain and is told that he must combat the seven crews of the pirate kings led by a mysterious leader known only as Black Beard Jack to stop them from activating each islands mysterious power and releasing their fallen captains.
These are just my initial ideas I'm going to to discuss them and see how it goes I've got another idea im pondering on at the moment but just stuggling to figure some key things of its world to drive the narrative forward.