The morgue seemed even more depressing at Christmas, mused John. He had been passing through and decided to come in quickly and reminisce. Remembering how he, Lestrade and Sherlock would come in for the body, often which Molly had prepared, with the latter making his fanciful deductions. No-he corrected himself-brilliant deductions. There was no way, he couldn't be a fraud, despite what everyone-even the man himself-had said.
John sighed. He had been keeping himself busy at work at the practice, and was even helping Stamford out with his teaching position at St Bart's. Filling his spare time, as to spend as little time as possible at the flat. Somehow, Mrs Hudson had allowed him to continue his normal rate, despite no other tenant.
He continued down the corridor, down to Stamford's office-he had nothing else to do at Christmas-when he paused. A muffled sound was coming from behind the door of one of the labs. Approaching to go open the door, the sound clarified into sobs and as the door clicked open, they stopped. John peered in and located the source of the noise.
Molly Hooper was sitting on a stool in front of a microscope on the bench. Not just any bench, realised John, but the one normally occupied by Sherlock Holmes during his research. She looked up at John with her swollen eyes.
"John? I-I didn't see you there... didn't know you were coming in..." she murmured, blowing her nose.
John went over to comfort her, placing an arm over her shivering frame. "What's wrong, Molly? You shouldn't be here, come on."
"Why are you here, then?"
John was taken aback, trying to answer the question himself. His confusion showing in his eyes, Molly broke down again. John embraced her into a hug. "It's okay, it's okay."
"I can't, I can't do this. I need to tell... I need to tell y-you," she muttered into his jumper.
"Tell me what?"
"... A-About Sherlock. I-" She broke off.
John took her by the shoulders, but then quickly moved back.
"What the...?"
Molly didn't respond, she just stared blankly as blue light surrounded her head.
John had seen this strange light before. He had been in Afghanistan when it had struck. There had not been many buildings, as they had been destroyed, so entire roofs were packed with people, unresponsive to the world. Later on, he had learned that it had happened all over the globe. That said, he remembered how the phenomena intended suicide for those unfortunate enough to be manoeuvred onto those rooftops. Falling off St Bart's would be perfectly fatal, as he so painfully knew. He restrained her, grabbing her arms, apologising as he went. The bruises and strains he gave her were nothing compared to the possible fate that the blue light had in store for her. He eventually guided her into a storeroom, where he locked her in and wedged a chair under the door handle.
Now that Molly had been secured, John headed upstairs. He was pretty sure no one else was here, but he was not leaving such a matter to chance. He rushed up the stairs, two at time, hoping he could cut anyone off before they reached the top, but there was not a soul that could be seen. He paused briefly at the door to the roof, silently praying that there was no one up there, and went outside. He closed the door and scanned the roof, his eyeballs freezing in the bitterly cold and windy weather. He was just about to go back inside to put an extra jacket on when he spotted the silhouette.
John trudged through the snow towards the silhouette, his eyes picking up the blue light and finer details as he approached. After only four steps, he stopped.
"No... No..." he murmured in disbelief.
John sat down in the snow, feeling quite faint.
Standing before him, in the exact position in which he last spoke to him, was Sherlock Holmes.
John sat there for what seemed like hours, barely noticing the gigantic rumbling that announced the arrival of the alien ship, or the cold that was slowly seeping into his bones. A million questions ran through his mind, about the now-hypnotised, supposedly-dead man, who now stood in front of him.
Sherlock Holmes returned to consciousness with an alarming feeling of deja-vu, over-looking the empty street below him. He stepped back quickly, not wanting to live out his nightmare, and fell. The snow cushioning his fall, he took a moment to fully comprehend his location. Sitting up, wondering how he had gotten to the roof of St Bart's, he noticed a shape in the snow beside him. Leaning in closer, he realised what the shivering mound was.
"John? John!"
Gathering his wits, he hefted his friend -who, he noticed, had lost a few pounds- up to a sitting position and dragged him unceremoniously inside. Shutting the door behind him, Sherlock slid down the wall into a sitting position. The loud bang of the door jolted John from his stupor.
"John..." started Sherlock hesitantly.
John, fuelled by adrenaline from the loud awakening, shock and grief, lashed out and hit Sherlock square in the nose.
"Yes, well, I suppose I deserve that."
"You bloody well do. Six months! Six months, Sherlock. I-I thought you were... dead," replied John, before breaking into a huge grin, with which Sherlock joined in. "How did you...?"
Sherlock took a deep breath, he had been waiting for this moment for a while, retrieving the rehearsed monologue from his head.
"After I had sent you away to Mrs Hudson, I went to Molly-"
"Molly!" interrupted John, remembering his efforts to protect her. "I forgot. I have to go get her. I locked her in a cupboard to stop her."
"Well then," said Sherlock, standing up, "let's go. I can explain on the way."
"You'd better."
Sherlock offered his hand to John, who took it and went into a short, rough embrace, thumping the taller man on the back.
"Glad you're not, you know..." said John, punching his friend in the arm.
"Dead," finished Sherlock, analysing the strange event which just occurred.
"Yeah, that."
Both men walked slowly down the stairs, Sherlock explaining his death-defying act, whilst steadying his friend whenever he fell, either from fatigue or just glancing too often at the miracle that was beside him.
Yeah, alright, it wasn't much of a crossover, but a reunion scene nonetheless.