So, just a thought, AlHaitham having a bad day. Like, his headphones stopped working, there were too many people coming into his office, there were too many loud noises (think modern au and there's construction on the street outside and it's summer/hot out so the windows are open) and everything seems to be going wrong down to the point of part of his shoes broke
So he gets home and he's just /miserable/. He doesn't even have to say anything to Kaveh for him to know, just tosses the broken items to Kaveh, collapses onto the couch with a pillow over his head in hopes of blocking out the noises.

It's house later when he realizes that he fell asleep. His headphones are sitting on the coffee table, his shoes are next to the couch, and there's a little note telling him to go into the kitchen when he wakes. He's still half asleep when he walks in, following the scent of spices and the sound of meat sizzling as well as the sound of quiet chopping.

He takes a seat at the table, head resting on his arms as he watches Kaveh cook, a tattered old cook book on the counter. It turns out that Kaveh was using his mother's old cook book that he'd kept and found some recipes that he figured AlHaitham would enjoy. So the rest of the night is spent between them with quiet conversation and AlHaitham with his head on Kaveh's lap, Kaveh's hands running through his hair as he gets to complain about his day