Obviously, Luffy and his dad are the most important characters. Luffy, the main character of the original story, is known for his carefree and determined nature. His dad, on the other hand, is a mysterious and powerful figure.
Well, in 'Luffy meets his dad fanfiction', it could be that Luffy's dad teaches him some new and powerful techniques. Maybe they team up to fight a common enemy. This would be a great opportunity for Luffy to bond with his father on a deeper level.
As of now, in the manga, the identity of Luffy's mom remains unknown. There have been many theories and speculations among fans, but no official confirmation.
There could be an original character created just for the fanfiction. A woman with a kind heart but a tough exterior, who was a great fighter. She could have met Luffy's father during a battle and they fell in love, and she became Luffy's mother.
Happy might also become Luffy's friend. Luffy would be amused by Happy's flying ability and his cute appearance. Happy could also help Luffy navigate the Fairy Tail world, as he knows it well. And Luffy might share his food with Happy, which would make Happy very happy indeed.
She could be a former pirate captain herself. Maybe she was one of the most feared pirates in her time, and her skills and reputation were passed down to Luffy in some way, even if he didn't know it was from his mother.
Since we don't have more details about 'Becky's dad adult stories', we can only guess about Becky's dad. He might be a father figure who experiences different events and has relationships with other characters in the stories. Maybe he is a kind father, or he could be facing some challenges that are central to the plot of the stories.
The dad of Peacemaker in the comics is Auggie Smith. Auggie's presence and actions have played a crucial role in shaping Peacemaker's journey and personality.