After nearly a month I am still stuck on Happly Married Old Gays Professor Gellert! and Headmaster Albus! AU, so here is another small headcanon that will make your teeth fall out from the amount of sweetness.
This one is called : Gellert and the art of DIYs. In particular, Gellert learning how to stitch.
Just imagine Gellert constantly complaining about being bored because Albus is always busy with his headmaster duties.
One day Albus forces Gellert to sit down and learn how to stitch, so that he has a way to kill time, instead of using it to bitch and moan and before he starts using it to plan some kind of mass murder.
Gellert, being Gellert, refuses at first but in the end he actually gives it a go bc you know, he's in love with Albus, he's a simp and he would do anything to make his husband happy.
So Gellert starts stitching things here and there, always muttering curses under his breath and looking annoyed as hell, because he has a reputation to live up to, and then he decides to stitch one of Albus' adorable pointy hats with little stars.
Problem is, the stars turn out all weird and wonky and wrong and so Gellert has a mental breakdown and gives up. Still, Albus loves the hat and his heart melts at the thought of his husband carefully stitching each star by hand.
So of course the hat instantly becomes Albus' favourite and he wears it all the time, all the while wearing a big, love-sick smile on his face. Needless to say, Gellert makes it his life mission to stitch Albus something new every week.
And they all lived happly ever after. That's it. Sorry for your next dentist appointment.