You were Zoro's little sister, you were 3 years apart he was 21 years old and you were 18 he was protective with you and he categorically refused that you be in the crew at first he ended up accepting after some conditions such as: not participating in fights, not putting him in danger and staying with him when they arrived in new countries and islands. You were not only Zoro's sister but also Luffy's girlfriend, it's true that he is very childish but he knew what love was, besides you sometimes wondered if he was really 19 years old he was never serious even in your couple he had the mentality of a child.