mousedetective MHAW Prompt #5: "Are you SURE I can't punch him in the face?" "Yes." "What if I just break his nose a little?"
Sherlock rolled his eyes. "Molly, you are freakishly strong for your size. If you tried to 'break his nose a little', you'd end up smashing half his face in."
The woman struggling (futilely) in his hold continued to glare at the smirking man standing in front of them. "Yeah? And where's the downside to that?" she demanded.
"The downside to that," Sherlock replied, wrapping his arms more firmly around her and lowering his head to murmur directly in her ear, "is that I probably couldn't get you out of jail in time for our dinner reservation, and tonight is of particular importance."
Molly stopped struggling, craning her head around to give him a quizzical look, completely distracted - as he'd deduced she'd be - by Sherlock's words. "What's so important about tonight?"
Before he could answer, their - adversary? foe? annoyance? - gave an impatient huff. "Because he's going to propose to you tonight, obviously. And no, it has nothing to do with your pregnancy."
That might have been the end of it if Mycroft hadn't had to just keep going. "Of course, he might have deduced it sooner had he not been so distracted by what ring to choose for you - ultimately, of course, he went for Grand-mere Vernet's emerald in a platinum setting, as I knew he would. Don't worry," he ended with a (definitely mock) sympathetic smile. "I'm sure he can have it sized down for you."
This time Molly was the one trying - well, I say trying - to keep Sherlock from being the one to slug his older brother.
(Mummy Holmes had absolutely zero sympathy for her eldest son's black eye when she found out it had all started because Mycroft couldn't help blabbing about Molly's 'interesting condition' just as she was about to tell Sherlock herself!)