It a mixture of a lot of one piece theories regarding luffy’s family.
First off , Instead of imu sama being luffy’s mom.I make imu sama as luffy’s great grand “mother”.
Because here how it works,
Imu sama is the immortal ruler of the world government (pronouns are them and they. despite this they prefer female fashion),But secretly yearns for freedom , but can’t because of the responsibility of running the government.
Quoting from a Reddit post, “To make it simple: Imu ……..related to ya boi Joy Boi and because she is a a ruler she Needs to act like one in front of everyone….”
Imu sama may not be able to experience “full freedom”. however ,when they did have free time ,they would traveled around the world and go sightseeing in a disguise.
During this they met a young man named……….
But during this time ,rocks isn’t a pirate yet.
Or maybe he is just starting out .
What happens between imu and rocks is what started out with a friendship then to lovers and yeah they banged.
Resulting a adorable baby girl ,The princess of Mary geoise. For now, we call her “Yriaf” for simplicity sake.
After Yriaf birth, rocks loves his daughter but still left to continue his pirate career.Which made imu bitter and harbor a grudge against pirates.
Imu and xebec broke up and went on to their separate ways,Imu takes Yriaf with them,But allows xebec to call from den den mushi ,writes letters and sent presents to their daughter ,Using a cipher pol agent (who swore secrecy )to deliver the mail.
Yriaf grew up to be a kind and benevolent woman despite being the princess of Mary geoise. She disliked the attitude of the celestial dragons and slavery. She treats people like her equal and tries her best to free the slaves and help treat/heal/nurse the injure/sick ones until they are healthy to go home or stay with her (she would pay them with wages)if they don’t have a place to stay.Sadly, she is banned from buying more than six slaves per month by imu sama.
Imu sama didn’t do this to be cruel,They are worried about Yriaf getting the wrong people’s suspicions. Imu sama honesty didn’t like the whole slavery system ,But the majority of the world nobles wanted this and imu have to go along. otherwise imu will become unpopular and risk getting deposed or worse case scenario,Getting Killed.
As much power imu has,Imu can’t protect Yriaf if all the world nobles voices their disapproval (Kinda like Grap’s situation ).
because of this ,Imu is strict with their daughter.Eventually Yriaf ran off to her father’s ship to get some fresh air from the royalty business. There she met her father’s crew and develop a relationship with one of the crew mate. Rocks is fine with it,after a long shovel talk.
Imu sama,However…… is a total different story.
Imu straight up disapproves.
But there is nothing imu can do, Other than sending cipher pol assassins to watch but not kill the crew mate who caught their sweet daughter’s eyes.
Yraif marries the crew mate,Whose name is Edward Newgate,Yes that Newgate.
Their child would eventually be known as crocodile.
Then imu noticed changes in rocks as the years goes by,How by each passing year,Xebec getting even more crueler and unhinged bloodthirsty ambitions thanks to his devil fruit that messed his brain, until imu no longer recognized the man they had used to loved.
For now,Xebec’s sanity is barely keeping together thanks to his paternal love for their daughter .But imu is not taking any chances if one day xebec snaps and cause irreversible harm to his own crew and potentially to imu’s family. Besides,Imu is still mad about xebec choosing career over them and the lack of child support other than toy stuff animals and unhealthy snacks. Yes imu can be petty like that.
So imu hires a hit on xebec, saying xebec is a terrorist threat and a crazy manic. Then sends a message to the elders to inform the navy of this dangerous individual.
Battle of god valley happens and imu takes back Yriaf. Gives her a decision to either take crocodile and never met up with Edward again or hand custody of crocodile to Edward and forbids yriaf from meeting them again, save for one day per 5 years. Imu allows for calling via den den mushi for during the whole time but that’s it .
The princess chose the 2nd option and tearfully waved good bye to her love and child.
Years pass, crocodile left the white beard pirate crew and joins the revolutionary. Also get knocked up by monkey d dragon.
When Imu founds out , they are not pleased , But At least they gets a great grand child out of it.