Sabo was born into a noble family, ran away and then became Ace and Luffy's spiritual brother when he was 10. He was kidnapped by his parents but managed to escape again, he took to the sea but was shot by a nobleman of the highest rank, Ace and Luffy thought he was dead, but he was saved by Monkey.D.Dragon, the leader of the revolutionary army. Unfortunately, Sabo lost his memory, but they came back as soon as Ace's death was announced when he was 20. After 2 years, he sees Luffy again