Sword of Rhivenia/Batman crossover where my SoR MC ditches the country after realizing she hates everyone around her and fakes her own death, fully transitions to a man (since she couldn't do it as a royal/queen) leaves for the United States. She uses magic to kickstart the transition process and leaves the sword behind.
MC makes his way into Gotham with a new ID just as Bruce Wayne/Batman begins his crusade and meets MC in both civilian and caped forms.
One thing leads to another, they get serious, Bruce confesses his secret identity, MC also reveals his origins.
They get together, and MC becomes Batdad.
The batkids know MC is trans, they DO NOT know about the royalty part.
One day, on a rare occasion where all the batkids are present and having breakfast together, a news report plays about the small country of Rhivenia, where the now King Richard and his children are at a parade, one of his children is a princess named after MC's old name.
MC scoffs and says the audacity on this man to name his child after him after the way things between them went down.
(Richard DID NOT take MC being chosen by the sword well, leading to their previously good relationship deteriorating at record speed)
MC even remarks that Richard only became king because he had better support than his sisters.
One of the batkids remarks that Richard sounds like a tool, another asks what does MC mean about the name. As far as anyone knows, the previous Queen, MC's former self, only lasted two years before she was assassinated.
MC says well, I was that queen, so I would know.
The batkids stop.
"Wait, what do you mean you were the previous queen?"
"I mean I was Queen (F/N) before I came here."
"what"
"Don't act surprised, you know this"
"No we didn't?"
"Dear, I don't think you mentioned that story"
"Yes I did? At least Dick should know, I told him I was a princess before"
"Yeah, and I assumed you meant you were a woman before, not literally!"
Que Various Noises from all sorts of questions.
"Alright! Settle down! I will tell you the story later. Now finish your breakfast, you have a long day ahead."