(insert this is fine dog somewhere in here) I'm having a time certainly!! I hope you're doing okay too akdjkckjfjh

INCHERESTING... hm HM HM..... For Alhaitham I think he absolutely wouldn't ever stop being annoying (affectionate) but he'd indulge him even more easily than usual, at least in everything except overworking - no work allowed on your birthday. But things like Kaveh casually mentioned that this kind of coffee or wine or snack is his favorite a few weeks ago, Alhaitham ordered enough of it for the other to live off of for the year lmao Kaveh's birthday is all about having him do everything he's been putting off for himself in favor of doing things for others, like resting, or visiting places, viewing art, seeing his friends - just having FUN.
He'd probably take Kaveh to any architectural landmarks or museums or lectures he hadn't experienced yet, or any he just wants to witness again, letting him marvel at them and talk Alhaitham's ear off mostly uninterrupted (because we ALL know Kaveh enjoys a little friendly debate every now and then too) - essentially he'd just turn up his adoring nature to 11.
It is of course also a must to get him his favorite food all day, and not let him deflect any of the affection he so deserves. He'll kiss him all over when they're home and snuggle and cuddle and be silly until they're all gross and sweaty from holding each other for too long and too tight in the middle of summer.

For Kaveh it's kind of the same but less overt in a way, there's no big dinners or friends or going out. Alhaitham's not the kind of person to want a big show made about him, but Kaveh knows what it's like to not have people there for you to celebrate the days that matter even a little bit. So he'd get all his favorites too, things Alhaitham probably forgot were even his own favorite lmao Kaveh definitely has the personality to remember things from years and years ago, but never over play them until suddenly you're sitting there nostalgic for this thing you'd fully forgotten existed.
They'd lounge ALL day because Alhaitham's sleepy after working and reading, and the sun is bright even in february and he never stops being obsessed with falling asleep with his cheek squished on Kaveh's chest, or vice versa, and because Kaveh knows deep down Alhaitham's favorite thing (and his) is just being together 🥺
Alhaitham's birthday is hard for Kaveh because it's just a day of trying not to let Alhaitham flip it into him spoiling Kaveh instead, they're just wrestling for treat dominance lmao
Kaveh like, but it's your birthday so I spoil YOU, and Alhaitham hits him with the well it's my birthday so I can do what I want and I want to do the spoiling - they're insufferable tbh 😔