[Well. Well, well, colour her surprised indeed. Out of all she expected, this certainly was not it -- though the slow smile dancing on her lips shows how pleased she is by this.]
You surprise me, Sherlock, by thinking you have to lay down the rules for me. I know you've never agreed with society's belief of how a relationship should function... and you must know my stance on it, as well.
[She reaches out with her hand, slowly setting it on top of Sherlock's, her tone low, her smile as close to a real one as it ever gets.] I would be delighted to accept your offer. There may not be many advantages to our stay in this sparkling prison, but this -- this I could never but believe to be one of them.