i do love the idea of john and sherlock memeing on their old misunderstandings ages later when they’re really settled into their relationship. like sherlock will just walk into the room like “hey mate” and john tackles him to the sofa and tickles him and kisses his neck in revenge. or john taking sherlock on a date and going “so…you have a boyfriend?” or sherlock will be like “hey john so im texting our client back but just fyi it does NOT mean im in love with her” and john is like HSJFKFKFKFK I SWEAR
Headcanon: For a long time John can't get Rosie to sleep so Sherlock plays violin or talks to her about science and Rosie just passes right out. For months Sherlock's voice or his violin is the only thing she'll fall sleep to.