Despite being enemies, Luffy helped Fujitora when Doflamingo’s thugs were cheating due to his blindness and thanked Luffy for his kindness.
During the Straw Hat Pirates and allies’ escape, Fujitora fought against Luffy until they escaped, to which he was taken aback by the latter admitting that he likes him. When Fujitora attempted to drop the rubble on Luffy, he was stopped by the cheering citizens of Dressrosa and decided to let Luffy go. Seeing how the citizens tried to help Luffy, Fujitora smiled and admitted that he should not have blinded himself because he wanted to see what Luffy’s face looks like. When Doflamingo’s business associates attempted to kill Luffy, Fujitora dropped the rubble on the enemy fleet as a farewell gift for Luffy and thanked him for cleaning up the World Government’s mess.
Despite her respect for Luffy, Rebecca reluctantly attempted to kill him after he won his group’s battle royale to better her chances of getting the Mera Mera no Mi. After her attempt failed, she is thankful to him for not retaliating.
She was overjoyed to see Luffy again when he came to her by a window. Luffy understands her feelings, so he asked her if she is okay with being separated from her father. When she said no, Luffy took her to her father. She is extremely grateful to him for everything he has done for her and was relieved when Luffy made it out of the country safely and hopes to see him again.
As news of Luffy’s actions in Big Mom’s territory spread across the world, Rebecca was proud of his progress.
Luffy’s treatment of Shirahoshi is similar to how Ace treated Luffy during their childhood, and how Luffy treated Koby when they first met: harsh and blunt, but shows some kind of care, and then friendly. Shirahoshi trusts in Luffy’s abilities and shows deep concern for Luffy such as when Luffy lost a lot of blood from the wound he received from Hody and when Luffy went after Caribou for the stolen treasures. As the Straw Hats leave, Shirahoshi promises that the next time they meet, she will no longer be a crybaby. Luffy also promises that he will take her to a real forest on the surface.
Though she was initially afraid of going to the Levely, Shirahoshi decides to go because she does not want Luffy to call her weak again.
Ever since Rayleigh had heard about Luffy from Shanks, he had wanted to meet him face to face.
Rayleigh, like Shakky, has great expectations for him after Luffy stated his belief that the Pirate King has the most freedom on the sea. After the war at Marineford, he swam across the Calm Belt to reach Amazon Lily, where Luffy had been recuperating from his injuries and from the loss of Ace. From there, he helped Luffy break into Marineford with Jinbe in order for him to send the secret message to his crew. Rayleigh also mentored Luffy on how to master all three different forms of Haki over the course of a year and a half.
After the two year timeskip, it is apparent that both of them became close from their training together. As he headed towards Thousand Sunny, Luffy shouted to Rayleigh that he would become the Pirate King, leaving Rayleigh with a smile and tears in his eyes. Rayleigh himself later proudly proclaimed Luffy as his pupil to the Marines. When Luffy set sail, Rayleigh compared his late captain to Luffy, claiming that destiny is slowly but surely taking shape, and that Luffy has become a man well fit to wear that Straw Hat.
Koby was one of the first people Luffy met on his journey. He traveled briefly with Luffy, acting as a temporary navigator after Luffy helped him escape from his servitude to Alvida. He later joined the Marines after the incident with Captain Morgan. The two also encountered each other at Water 7. Although they are now on opposite sides and will inevitably have to fight, Koby and Luffy still consider each other friends, since Luffy helped Koby muster up the courage to become a Marine.
During the Battle at Marineford, Koby chose to fight Luffy only to be swiftly defeated by a punch to the face. Despite that, this has not damaged their friendship, as Koby still admires Luffy’s strength.