What if the batkids call Bruce "Dad" only in their civvies, but then call Batman "Mom"
It started with Dick pondering about the whole "secret identity" thing as a young Robin. The news are partially about Brucie Wayne, young dad extraordinaire setting an example for all reformed rakes turned fathers.
Then half of it is about speculations on Batman's true form — because while they all could've sworn that Batman was, well, a man... most investigators are hesitant to consider him human now because suddenly there's a toddling colorful child creature bobbing along after the living legend, with the same moves and capabilities as the Bat
Dick gets the brilliant idea to make Bruce into it
"Think about it!" Dick said on that first patrol, "People won't think too harsh on Batman if they figured that I'm just your little cub who is also made to fight crime, instead of a human kid out on the streets at night."
Bruce narrowed his eyes, but there's no harshness in his gaze. He's looking at this little boy, with messy curls of black and the sweetest shade of blue in his eyes. A reflection of him. How cruel it is of this boy to play with his feelings.
"You want people to think that the Batman is a creature that can give birth?" Bruce repeated carefully.
"More than that! I want them to think you're my mother!"
It works as Dick proposed. Lesser ties made to Bruce Wayne, a cisgender man who can definitely not give birth, to Batman, a creature that allegedly birthed Robin. Bruce thinks it's the stupidest solution to a common problem, and he made Brucie.
But it works so they let the story run wild. Bruce doesn't mind so much as the weird, hungry, curious gazes that some villains and thugs give him.
Dick seemed to find it hilarious when ladies stopped Batman in the streets to tell him to rest because "you just gave birth!!"... only until said people also tell him to "respect your mother!"
Overall, it was just another one of those weird things a vigilante resorts to for the sake of operational efficiency...
Until one time, Robin had gotten captured in a ship rigged to blow, and villains left and right were hitting him everywhere.
Batman had priorities on the other side of the docks. Robin just had to distract everyone else, and this was a distraction technically. But everything hurt and some of the older men were looking at him funny and he can't move and he wants to go home.
"MAMA!" Robin shrieked into the night.
And descended from the shadows was the Batman, in all his apparently motherly glory — towering above 6 feet, maybe more, because animals grow their appearance when preparing to pounce. A culmination of darkness and rage. Armed to the teeth with weapons and artful precision.
His white eyes turn to a bloodied, shaking young Robin, then to the rest of the fools who dared breathe his boy's air. The sound of rage he made was not human.
Every move is calculated and efficient; not with the aim to kill, but to make an example of the bastards who dared hurt his little bird.
This story will be passed along the underworld of Gotham for years to come as more and more of the Bat's brood grew
And this secret will be inherited from Robin to Robin, Batgirl to Batgirl
Bruce is a father — providing, stern, careful
But Batman? They each came from his symbol, his cloth, his rearing. And Batman is a much more violent creature when it comes to protecting those who have his mark.
If that's not a mother, then what other deadly creature can the Bat of Gotham possibly be?