Just some headcannons I thought of
Marinette is 18 and 5 feet tall. There are downsides to this of course. Jason's teasing. He calls her short stack often because she's well built yet barely reaches the chest of anyone in the Wayne household. A pro to this is when playing in the annual hide and go seek tournament amount the siblings. She even managed to hide behind Alfred as he was standing still watching in amusement. Also as Ladybird (she changed her hero name and costume) due to her small size she can sneak up on villains or rougues easily and even managed to sneak up on batman (yes yes she did). But she's stronger than she looks, and accidently broke 5 ribs in jokers chest when he broke out of arkham again. If she had kicked any harder she would've made both lungs collapse. Jason was a proud honorary big brother.
Sometimes even Damian teased her about it when they were alone in his art room. He hugged her almost to the point of suffocating her to prove his point when she huffed and claimed she wasn't that short. He'd hug her from behind too and kiss her neck just to see her reaction.
She had to climb on the counter just to barely reach the flour on the top shelf. Every time she can't reach something she reluctantly asks for help because even though she could make herself levitate, she refused to use her powers for something so simple.
Even when Damian and Marinette got married at ages 25 and 26, she was still only 5'1. I can only imagine how they danced at galas with such a dramatic near foot and a half height difference. Marinette blamed genetics. On her mom's side of the family, her tallest ancestor was only 5'4.
Make no mistake however despite her size, when her and Damian get intimate, she's never afraid to take care of her man occasionally. (If you know what I mean..............).
Any ideas or requests? I'll try and update but I feel writers block coming soon.