Remus / Sirius
Yes, they'd done things together that were far dirtier and scandalous than Sirius kissing his cheek, but even the simplest thing still became something that took Remus by surprise. It would likely never stop shocking him that someone as beautiful inside and out like Sirius could ever love someone like him the way he did. He could be with anyone, truly anyone in the whole world and he wanted Remus? Well, that was more of an honor than Remus ever felt he deserved.
Sometimes it did take a lot of poking and prodding to get Remus to give in to Sirius but that was usually just a way of dragging it out because they both knew he'd eventually give in. Sirius being dramatic was endlessly entertaining -- listening to his ridiculous line of reasoning brought quite a bit of humor along with it, and Remus admittedly liked it. It also just kind of... made him feel good? Knowing that Sirius wanted to spend time with him so much that he'd come up with the things he did -- for someone like Remus, it meant the world to him.
"C'mon, you," he said, and took his boyfriend's hand. "Show me how it's done."