Though Luffy doesn’t have any brothers related to blood, but he has two adopted brothers such as Ace and Sabo, although they are not related by blood. Their bond is so strong that they consider each other true family. Luffy, Ace, and Sabo formed their brotherhood during their childhood in the Goa Kingdom.
Portgas D. Ace :
Portgas D. Ace is the son of the Pirate King Gol D. Roger. He was Luffy’s older brother and a fierce protector. Ace possessed the power of the Mera Mera no Mi (Flame-Flame Fruit) and became a powerful pirate, eventually joining the Whitebeard Pirates. Sadly, Ace gave the biggest sacrifice of his life to save Luffy during the Marineford War.
Sabo :
Sabo is Luffy’s other adopted brother and he was previously believed to be dead after an accident involving a Celestial Dragon. However he survived in that incident and later reappears as one of Luffy’s most powerful allies. He also inherits Ace’s Devil Fruit power, continuing his legacy and strength.