Roronoa Zoro is the combatant and the swordsman of the Straw Hat Pirates. Being the first person Luffy recruited in his journey to the One Piece, Zoro holds paramount importance in the story.
Although Zoro is Luffy's subordinate, he has great ambition himself, much like the other members of the crew. He aims to become the greatest swordsman of his time and reach the very top to keep his promise to his best friend, Kuina.
Read more on gamerant.com