Playing with his hair when you kiss, or just to annoy him or when you lay in bed together.
Calling him “Holmes”
Sherlock wouldn’t introduce you to Mycroft for a while because he would be worried Mycroft would make you leave somehow. But when you did get formally introduced to Mycroft it would be a little strange… “Oh this is your brother? I met him the week I met you in a coffee shop. We had a nice little chat! What a coincidence.” You would all know it definitely was not a coincidence.
Sherlock would teach you to dance. He would be shy about it at first but once you’d stepped on his toes a few times and looked so shocked and apologetic afterwards he wouldn’t be able to stop laughing.
Telling Sherlock you won’t talk to him until he eats something substantial. “Oh, you’ll crack eventually.” You don’t. Sherlock ends up aggressively eating a sandwich in front of you while you burst out laughing - he’d had enough of asking your opinion on a case and you just giving him an eyebrow.
Sherlock takes you on cases with him because he likes you to see you (impress you).
You keep laughing at inappropriate times, earning the eyes of everyone at the scene. “Sorry, it’s just that that’s Sherlock’s um… face.”
Taking baths and showers together because you can both be absent minded in the shower and this helps you save water.
John wouldn’t know for a week or so that you two were actually dating. He would’ve thought that you didn’t swing that way so he would be very shocked when he walked in on you and Sherlock making out. “Is this um… for a case?”
You and Sherlock would dress and undress each other (mainly for motivation for Sherlock) as he would often not bother to get dressed and would stay in the same clothes for days. This way you did it for him (which he quite enjoyed).
Subconsciously imitating his clothing style. You don’t realise until there’s a photo of you two in the newspaper.
Laying on his lap when he’s reading through papers
Mrs Hudson would adore you. She would keep asking when you two were going to get married.
It would make Mycroft uncomfortable to see his brother so happy with someone in that way.
Meeting Sherlock’s parents. They have many funny stories about Sherlock to tell you.
Sherlock suddenly going to you at random times, holding you by the shoulders and half yelling at you because he’s “realised why I feel this way about you”.
Standing up for him with cutting comments whenever someone insults Sherlock. You’ve picked up on how to hurt people with words (you don’t use it very often though).
A lot of hand holding but not that much else PDA
Imitating him when he’s being stroppy. This causes him to imitate you back and you’re both strutting around the flat in each other’s clothes , shouting mockery at each other until Mrs Hudson bursts in laughing. “You two are so strange! You’re perfect for each other!”
When she leaves, Sherlock turns to you. “We are you know. I mean, statistically speaking.” “What?” You laugh. In answer you just kiss each other, him in your clothes and you in his.
“Does it make me self indulged to say you look really hot in my clothes, Sherlock?” “Perhaps. But I do have to agree.”