Upset
"Molly."
"What do you want?"
Sherlock regards her for a moment, trying to think of whether it would be appropriate to ask her for assistance at the moment, considering her entire demeanor looks quite gloomy and there's a hint of underlying sadness that she's trying very hard not to show. "What happened?"
Molly frowns at the question. "What do you mean, what happened?"
"You seem very… defeated today, for lack of a better word."
She cringes at the term that he chose to use, but there is no way she is telling him what's wrong. She herself thought it was a stupid reason to be sad, he'd think she was downright crazy for being affected. So she just shakes her head. "No, I'm perfectly fine."
"You look upset."
Another cringe. He just knows how to use all the right, or in this case, wrong words, doesn't he? "Just tired."
"You're barely halfway through your shift."
"I barely got adequate sleep last night."
"You don't have bags under your eyes."
"I covered it up with make-up."
"You're not wearing any."
Molly sighs. She just can't win today, can she? "Seriously Sherlock, it's fine. What did you come here for? There are no new bodies, but there is a new set of organs for study, if you want."
"No, I just needed to check on my experiments." he said casually, walking towards his microscope even though the eye on the back of his head is firmly placed on the obviously dejected pathologist. What could be troubling her?
They don't speak anymore, partly because Sherlock doesn't know the right questions to ask her, and partly because Molly wouldn't know how to answer them right now without seeming like a complete fool.
Note: This one would be up to the reader, the reason as to why Molly is down today. The author has her own reason, and just as Molly was, she'd look like a complete fool if she revealed just what that reason is.
On a lighter note, she's still very much anticipating more Sherlollians to join the challenge. Wouldn't it be nice if, say, in ten months' time, Sherlock/Molly had 10,000 fics in its archive? :)