A/N: Somewhat inspired by Flaignhan's Schoolgirl Crush but then it sort of took a life of its own. I really liked the strong Molly Hooper from the last episode of Season 3 so I wrote her like that. And, sort of my take on why Molly Hooper doesn't reappear again after that scene. I hope you enjoy!

Spoilers for 3x03 – His Last Vow

I don't own Sherlock or any of its characters.

Out of all the hurtful words and the brush-offs that Sherlock served out to Molly over the years, no cut ran deeper than when she saw the results of his drug test that day. She hadn't believed it when John first brought Sherlock in, although the signs were all there. She knew from his unfocused eyes, his sickly pallor, his protruding veins underneath the grime, and even through his slowed speech that he had fallen back in. After all, she spent most of her formative years of university with this Sherlock. She would know him anywhere but she had refused to believe her own eyes because he had promised her. He had promised her. And she had believed that out of all promises, he would have kept this one because he had put her through the nine circles of hell when she had gotten him clean the last time. She had stood by him when no one else had and she had been there every single fucking day, making sure he didn't die.

And he had known. He had known that he would have died without her so when he had finally gotten clean, he had taken her hands, looked in her eyes with his own watery ones and had promised her, that he would never, never, become that Sherlock again.

And she had believed him, which was why the results under her microscope left her feeling numb. But only for a moment, then the hot, pulsating heat of rage and disappointment began to take over.

She knew he was sorry. She had known that he felt guilty the minute he stepped into the lab because he hadn't looked in her direction even once. She saw the way that he closed his eyes when she finished her testing. She had also known that he knew that he deserved those slaps and so much more by the way he was unsurprised when the first slap came, and the second, and the third.

That's the thing. She knew Sherlock. She could read him as easily as he could read the rest of the world so when he had promised her that he would never touch the stuff ever again, she knew he was being honest. She always thought that Sherlock may be a cruel bastard but he was never a liar. So this betrayal, this broken promise cut deeper more than any other.

He could tell that she had cried. Even John could have got that. Her eyes were red-rimmed and her make-up was smudged then scrubbed off. That's the first thing he notices. The second is that she is sitting in his chair. No one sits in his chair. The third thing he notices is that she's refusing to look at him but instead at the fireplace. He looks there too and notices what exactly is burning there. He swiftly turns and goes to his room, searching through all his hiding places. He steps back, shocked. Then slams out of his room to the kitchen and searches there. Then the bathroom, then the hall, then John's room, then finally, the living room. Nothing. He looks at her, dumbfounded. She continues to stare into the fireplace, as calm as could be even though she had accomplished in thirty minutes what a team of professional investigators couldn't in hours.

"Surprised?". Her voice breaks the tense silence and it is a voice raw from crying.

Sherlock inwardly winces.

"I can easily get more."

Her eyes flash to his. With lazy movements that bely the anger pulsing under the surface, she gets up to stand in front of him. "You can try but your regular dealers won't go anywhere near a 5 kilometers radius of you and I'm guessing they're spreading the news that you are not a client to be dealt with. In approximately 3 hours, every drug dealer in London will know better than to give a Tylenol, let alone any hard drugs of any kind."

He tries not to look impressed but he's so used to underestimating to Molly that when she fully displays her intellectual prowess, he's always taken by surprise. He forgets that she's not like the other goldfish and that is never more proven than when she's on a mission to save Sherlock.

"And how exactly did you manage that?"

She gave a small cold smile, one that he had never seen on kind, innocent Molly Hooper's face before. "I told them that if I caught them giving you drugs of any kind, I would make sure to personally administer a dose of Mad Cow's Disease, Salmonella, and West Nile Virus in their bloodstream that not only do they die, they would die a slow, painful, horrible death.

This time, he can't suppress his surprise. He had never seen this side of Molly before and again, he was impressed. He could tell that she had meant every word. He keeps forgetting how this woman in front of him would do anything for him, even commit murder, it seems.

He opens his mouth to give a snarky retort but she cuts him off.

"I have known you most of my life. I have been with you through every important and unimportant moment of your life." She looks at his ice blue eyes. "You have not been there for mine, but I knew your nature so I understood. I knew how you were with sentiment and how hard it was for you to express it but I have always known that I meant something to you, something more than everything else because I am your first and for the longest time, only friend."

For the first time, Sherlock feels a ball of tight fear growing in his belly.

"I have spent five years of hell watching you kill yourself with these drugs. I placed the most tragic event of my life, the passing of my father, on the backburner so that I could be there for you. I have watched you tiptoe the line of life and death more times than I can count. I know that you have no idea what that felt like that but maybe you might have some idea now that you've watched John's life be threatened. I can guarantee what you felt then does not even begin to scratch the surface of what I felt when I was watching you because I couldn't do anything. But even though it was killing me, I stood by you because I was your friend and because I love you."

Finally. She had said it. She could feel a burden lift off her chest at finally saying those words that she had kept hidden for so many years. In the next instant, her heart clenched again at the words she had to say next.

"And I knew that I meant something to you when you finally came out of rehab and you looked at me and you promised that you would never place me in that position again. And I believed you because you might be a cruel bastard but I knew that you weren't a liar."

Sherlock looked away from her burning brown eyes. Every word she was saying was feeding the fear in his stomach but he refused to let it show.

" Then you met John." He looked back at her. "And you became cruel again. I was treated like nothing again but that was ok. Do you know why?"

He shook his head, wordlessly, because he honestly had no idea. John used to lecture him about how horribly he treated Molly and sometimes Sherlock would wonder why Molly took it from him.

She stepped closer to him, with tears in her eyes. She laid a hand just above his heart.

"Because you were finally showing someone the heart that I always knew you had. I was so happy for you, Sherlock." A tear ran down her face and her lips trembled. "I was so happy that you found John and that you finally allowed someone to enter your heart. I was willing to bear any of your cruel words for that. I was ok with John taking my spot as your friend because I had thought-"

She bowed her head, shaking the emotion out of her voice. She looked up at him again with clear eyes now.

"I had foolishly thought that if you could open up to John that there might be hope for me. I thought that if you could have a friend then if I just waited patiently that, someday, there would be a place for me."

He looked at her, confused. Then understanding dawned and suddenly, sorrow overtook him. "A place for you as something more than a friend."

She nodded, tears running freely down her face. "I had always thought if there was any place in your life for someone…. Romantically, that it would be. I clung to that hope." She swallowed a rising sob, her whole body trembling from the effort. She refused to break down in front of Sherlock. Not at this important moment. "I thought that, finally, that moment had come when you came back because you were so kind, so thoughtful, and you were trying so hard." She looked at him, guiltily. "That's the reason that I broke it off with Tom. I had thought that I would never be content with a copy when the original was finally within my grasp."

Her gaze turned desperate now and Sherlock sudden had an urgent panic to stop her from saying her next words. But no words came out. The fear that had started in his stomach had now wind itself around his body, squeezing his throat, preventing him from saying a word.

"But you broke a promise today. You broke the most important promise to me." She grasped his arm. "And I know that I could probably do it all again. Stand by you to make sure your life is on track, killing myself while I do it because I love you that much. And when I walked into your flat today, I was going to do just that. I was willing to put myself through that hell again to make sure you're ok because I knew. I knew that I had that place in your life so I was willing to be there for you."

The tight coil around Sherlock's body loosened. This was his Molly, the one that would never leave him. The one constant in his life.

Molly's hand slowly slid down his arm, grasping his hand.

"But I found out something today. So, now I'm done. I have to quit you now, Sherlock, while I can still build something with my life before you totally consume me. This is it, Sherlock."

Sherlock went numb then a pain, more intense than he had ever felt, exploded in his chest.

"I found out something today, Sherlock, and that is, I no longer have a place in your life."

And just like that, Molly Hooper walked out of his life, leaving only a pair of Janine's underwear in his hands.

The End

I hope you guys enjoyed it. It was just a story that's been rattling on in my head for the whole day and I just needed to get it down so I could go back to studying my Clinical Forensic Psychology course. Anyways, I would love to hear your comments so please review! There may be a companion piece to this if I have time to write one and if I have the inspiration.