shizaya headcanon: izaya and shizuo aren't the happy lovey couple. they are the couple who'd be at each others throats in their home and outside their home but like,, every other blue moon they'd be like,, "i hate you but your glasses are ok i guess" or "your knife skills are mediocrely competent" and then they're back at it again
Although I love affectionate relationships, I can definitely see Shizuo and Izaya not being so affectionate. That’s not how they are. Izaya and Shizuo both distance themselves from people in fear, so being in a relationship works be an alien concept that would be perfect for them to share together. They would find ways to show affection that suits them.
Shizuo holds back his punches, puts the kettle on when he wakes up so Izaya can have a drink when he wakes up, leave his clothes on the ground less and less because Izaya hates mess.
Izaya makes sure only to cut skin when Shizuo’s wearing a shirt he likes, recommends books to Shizuo so they can share another hobby, sits beside him on the couch despite his distaste for affection.