Silvers Rayleigh

Who is he? Silvers Rayleigh, also known as the “Dark King,” was the vice-captain of the legendary Roger Pirates. He is an experienced fighter, a master of Haki, and played a crucial role in exploring the Grand Line. After the death of Gol D. Roger, he retired and lived as a shipwright on the Sabaody Archipelago.
Rayleigh first meets Monkey D. Luffy during the Sabaody Archipelago arc. There, he helps him and his crew members after they were attacked by an admiral and the Pacifista.
Why is he a loyal ally? After Luffy was separated from his crew following his defeat against Bartholomew Kuma, Rayleigh sought him out. He became his teacher and trained him for two years on Rusukaina, teaching him the basics of Haki.
Thanks to this training, Luffy was later able to fight strong opponents like Big Mom’s and Kaido’s commanders. Although Rayleigh does not actively interfere in Luffy’s adventures, he firmly believes in him and sees in him the potential to usher in a new era.