The Marriage Proposal Negotiation

Sherlock hasn't ever really done anything the traditional way, so of course it wouldn't bother him to propose to John even though they're not even dating. And the fact that John is already on a date with someone else when he decides to do it? Tedious.

“What are you doing?” John asks quietly, angrily.

“I thought that was fairly obvious,” Sherlock replies calmly.

John sighs, rubbing his left hand over his eye, “You can’t just propose to me so that I can’t date anyone and have no choice but to keep coming on cases with you.”

“Marrying you myself is precisely the only thing I can do to stop you from marrying and leaving again."