Original: Finding the last piece of Barbaros in a chest in the captain's own castle, Zack rings Wiki in order to return Barbaros to his former self. This restores Barbaros' humanity, but also reveals his true intentions, that he never planned to give Zack anything and wishes Treasure Island all for himself.
Simplified: After Zack and Wiki find all of Barbaros' parts and revives him, Barbaros betrays Zack and Wiki to keep his ship and treasure, and returns to Treasure Island.