Set 5 months before Sherlock's return.

You're never to old for a shoulder to cry on.

It was the "Shit, shit, fucking shit." followed by a very loud nose blow that alerted Mary to the problem. She was walking past the ladies loos en route to the library, her laptop and handbag over her shoulder and the latest copy of the British Medical Journal tucked under her arm.

Pushing open the door Mary was confronted by a dishevelled and red eyed Melanie Stevens who was glowering at her reflection in the mirror as she tried to salvage the remains of her makeup, tears still washing it down her reddened cheeks.

"Melanie, do you need help?" She didn't ask if she was OK, because it was fairly clear that her student most definitely was not.

Melanie turned, shocked that someone had discovered her. She dabbed frantically at her still tearful eyes and looked desperately for an escape. "Professor! Sorry. It's fine, I'm fine. Really. It's nothing. Allergies."

Mary gave an exasperated sigh. "Melanie, do you really think you can bluff an expert in tropical medicine that you are suffering from allergies? And you are clearly not fine. What on earth has upset you? Is it Declan?"

Melanie and Declan O'Riordan were notorious for their on-off relationship, loud arguments and even louder make-up sessions. They were one of those couples that formed the focus of the IT crowd, and who thrived on the confrontation in their relationship. Despite both being close to thirty, and being highly intelligent and skilled doctors, when it came to each other they behaved like stroppy teenagers, bringing out the worst in each other and their small but intimate circle of friends.

Melanie sniffed loudly and used the already sodden wodge of tissue to wipe at her nose. "It's alright Professor. It's just, you know, relationships." That seemed to tip Melanie's emotional balance as she doubled over and began sobbing again.

Mary hung her bags on the hook by the door and tucked her BMJ into the side pocket of the laptop bag, unwilling to risk it to any of the surfaces in the public toilet. It looked like she was unlikely to make it to the library today. With a sigh she stepped forward and took Melanie's shoulders, guiding her backwards into one of the cubicles.

Flipping down the toilet lid and giving it a cursory glance for cleanliness, Mary guided the young woman to sit on the closed loo, while she grabbed another handful of toilet roll to mop up the latest deluge of tears, snot and saliva. Understanding anything that came from the distraught woman was nigh impossible, so Mary settled for making consoling noises and rubbing her back until she calmed down. It took 20 minutes of tears and wailing before Melanie finally cried herself out.

"Now Melanie, do you want to tell me what's wrong?"

"It's … it's Declan. He was laughing with Seb and Rahjit. Making comments about me, how I look, what I'm like in bed, that kind of thing. Talking about me like I was a possession, not a person. Those things are private, between us, and he was boasting to his friends about it. Then he started going on about how he was going to get me pregnant as soon as we were married. How he's going to set me up in a cottage in Wiltshire surrounded by babies while he works in some Government research facility down there. Apparently his dad's already lined him up with the job."

Mary sighed. "And I take it this is not what you want."

Melanie wailed again. "NOOOO! We've never discussed marriage let alone children. He's just taking me for granted and I hate it. He knows I want to do research overseas. Maybe volunteer for humanitarian aid. See the world. How … how could I have been so wrong about him? He's just another sexist pig."

"Hmmm, well, I can't really comment, but it sounds like you two need to have a serious talk about expectations and appropriate behaviour. You have the right to do what you want with your life, not bend to the will of someone else just because of sex."

"But I don't want to end up alone. I'm almost thirty already. I don't know if I want children, but I don't want to leave it too late."

"Oh dear girl. Children are not the be all and end all, and if you're not sure you can always have some eggs frozen, should you change your mind at a later date. Also, don't forget the wonderful invention of the sperm donor. Don't marry someone just because they're available and you're scared of the future. Work out what you want and go from there. It's your life and they're your dreams. A very wise friend of mine once told my mother that 'no-one should have regrets except those of their own making.' A sentiment I wholeheartedly agree with."

"But it's OK for you. You're engaged."

"I am. To a wonderful man who I love very much. But that doesn't mean I didn't pursue my dreams, as he pursued his."

"Don't you regret it though, giving up children to have a career?"

"No. Not at all. I didn't give up anything. I've never wanted children, and John's perfectly fine with that."

"So, if he suddenly said he wanted children?"

"That's not going to happen. We talked everything through very early in our relationship. We both went in knowing what we wanted, and especially, what we didn't want. We also know that we trust and respect each other, which means I trust him not to boast about personal information, just as he trusts me not to. We have an equal partnership."

Melanie sniffed, dabbing the ball of tissues to her nose.

"So what do I do?"

"Well, that's up to you, but if it were me, I'd have a long hard think about what I truly want in life. Remember it's not an either or. It's possible to have children with a successful career or without a husband. It's what you want that matters. Then I'd think about what I want out of any potential partner, then I'd have a long talk with Declan. If that means dumping his sorry arse, then do it. Possibly in front of Seb and Rahjit, just to drive the message home. Not that I'm telling you what to do, of course. I'm just saying, if it was me, that's what I'd probably do." Mary felt a twinge of guilty embarrassment. She knew Declan liked to be the big man, but his behaviour towards Melanie won him no prizes in Mary's eyes.

For the first time since Mary entered the loo, Melanie gave a small smile. As she thought about what Mary had said, her face slowly developed a look of determination.

"Thank you Professor. You've been a great help. I s'pose I've got a lot to think about."

Mary watched as the puffy faced but resolute woman gathered her things, gave the Professor a grateful smile, then headed out into the corridor, still sniffing and dabbing at her nose, but with her shoulders back and her head held high.

Two days later the talk of the campus was how Mel had very publicly denounced Declan in front of his crowd of cronies as a "selfish, mysoginist pig who didn't deserve a woman like her." How he was a pervert who talked her into doing things she didn't want to do and then bragged about them. And how he could "shove his 'perfect life in the West Country' up his sexist arse." Apparently the determined Mel's parting shot was how he needed "a brain-dead trophy wife, not a brilliant, intelligent, and frankly gorgeous woman like me."

Mary smiled, then placed the information about the University of Oxford Centre for Tropical Medicine and Global Health into an envelope addressed to Dr M. Stevens. She included a post it note reading "If you're serious about this, or MSF, I'd be happy to talk to you. I've got contacts. – Prof M. Morstan. PS – nicely done!"