Jim would make it very clear to everyone (especially Sherlock) that you were his.
Anyone even remotely threatening to your safety wouldn’t get within ten metres of you.
Going out for extravagant, elegant dinners and dances when Jim had managed to clear a restaurant/location for the two of you. These dates would all be last minute so Jim would supply you with suitable attire.
“If someone pulls up in a car next to you, you must not get in, alright?” This backfires on him later when he picks you up and you ignore him just to annoy him. “(Y/n), get in the fucking car.”
Even though he would be possessive, it would be sort of behind the scenes possession. As in he would tell you you could do whatever you wanted but would keep an eye on you. If he wanted you in a specific place or to spend time with him he would someone manipulate you into doing so.
Calling him Queen or King.
He would call you “Kitten” or “Jewel”
Sherlock would finally meet you when Jim sent you to 221b on a “diplomatic mission”. Really, it would be an exercise of Jim’s power, showing Sherlock that even in his own flat, no harm would come to you.
Sherlock would find you quite fascinating because you hadn’t bored Jim, which seemed unusual.
You would just smile slyly as Sherlock tried to deduce you, (this would annoy Sherlock even more).
Jim would kiss you with a lot of force. It would be exciting yet terrifying.
Whenever you made a sarcastic remark to Jim he would imitate you, “Oh I’m outsmarting my boyfriend ohh” You’d laugh, sticking your tongue out at him. Jim would smirk, asking you if you wanted to put that tongue to better use. (Depending on his mood he may just pull out a lollipop.)
He would buy you a crown.
Jim would enjoy making you tea for some reason. Whenever you had to buy him a gift you’d get him fancy tea cups.
When he was in a rage and smashing things he would usually hesitate to smash the teacups you gave him. This hesitation would cause him to calm down slightly.