Guest, Luffy and Sabo were sworn brothers in childhood, always getting into mischief together. Guest and Nami dated when Nami managed to escape from Arlong. Guest is a Devil Fruit user and also has all three Haki, but after fighting Arlong once in the past and injuring him, Guest became wanted by the Navy. Guest and Nami sadly agreed to break up—Nami didn't accept it at first, but Guest didn't want to put her in more danger. One day, Guest was passing by an island and saw a Jolly Roger with a straw hat. He went ashore, and when Nami spotted him she was shocked. When Luffy saw him, he got super excited to see his older brother again, and his current crew: Zoro, Nami, Usopp, Sanji, and Chopper, didn't even know he had a brother.

Luffy: "Guest! Long time no see, big brother!!"

Nami was even more shocked by that news—her captain is her ex's brother.

Nami: "Brother?!! You two are brothers?!"