Joan had just got home from her morning jog and had blended herself a smoothie when the letterbox rattled. She frowned in confusion. The mail had already been lying on the floor when she'd arrived. Sherlock was busy with his morning ritual of watching numerous things on TV and she knew better than to interrupt, unless she wanted to be quoted at for the next ten minutes. She sighed and went to satisfy her curiosity.

On the floor lay a small brown envelope with 'SHERLOCK' scrawled across the front. There was a faint blue-white glow shining through and Joan's frown grew deeper. She picked it up and it felt like something small and heavy shifted the weight inside. She decided that it was okay to disturb Sherlock for this.

He was standing in front of numerous TV's, his head darting from screen to screen. He was shirtless and Joan was momentarily distracted by the tattoos on his back and shoulders. She was monumentally curious about what each one meant, but her pride kept her from asking. It still confused her as to why a man such as Sherlock would see a use in something such as a tattoo. Of course, it had to be for a use, there were very few things that Sherlock Holmes did that didn't have a use in that huge brain of his.

Remembering the envelope, Joan cleared her throat loudly. As expected, Sherlock didn't show any inclination of acknowledging her so she ignored this and started talking like he was a normal person who listened to people.

"This envelope came for you in the mail," she gestured with it slightly even though his back was to her.

"I often get letters in the post Watson, it's not normally worthy of declaration," he said, not taking his eyes off the screens. Joan thought she might strangle him one day.

"It didn't come with the rest and it doesn't have an address on it, like it was hand delivered."

Sherlock's head turned over his shoulder in mild curiosity. Not so he was entirely facing her, but at least indicating that he was listening, if only for the moment.

"And what may you deduce from this envelope?"

Joan stifled a sigh. Of course, everything had to be some sort of lesson; she wouldn't be surprised if he'd sent it himself.

"Well the name on the front is handwritten, meaning that whoever wrote it didn't worry about it being traced back," she offered.

Sherlock had turned around and was heading towards the kitchen, but he nodded and motioned for her to carry on.

"It was hand-delivered, so maybe it was too delicate to be trusted with the regular mail?" she shrugged at this bit knowing she was clutching at straws now.

"Letters aren't often fragile Watson," Sherlock stated simply. He was pouring milk into a bowl of cereal.

"It's not a letter though, it's solid, and glowing, what am I supposed to deduce about that?" Joan made her tone as sarcastic as possible. She braced herself for a witty remark but instead the envelope was ripped from her hands.

Sherlock had jumped across the room as she was talking and now moved hurriedly towards the table, tearing open the envelope as he went.

He swiped away the remnants of what was left on the table and emptied the contents. A small vial clattered into the empty space.

Joan couldn't help but stare. If she didn't know it to be impossible, she would have sworn the vial was filled with light. She supposed it must be a liquid of some description, but never before had she seen anything glow so bright.

It was a moment before she noticed Sherlock's reaction. He had turned away immediately, his hands on his head in obvious distress.

"Sherlock, what's wrong?"

He didn't reply. Joan hadn't seen him this upset since he had last spoken of Irene. As always she felt a compulsion to help him, to take away as much of his pain as she could. And, as always, she had no idea how.

"Sherlock?" she ventured again.

"I need to go," was all he said. His voice seemed close to cracking, not through tears but through panic.

"I'll go with you," she replied, determined not to leave him alone like this.

"No!" he yelled suddenly. Joan jumped slightly.

"I'm not going to leave you," she began to insist but Sherlock grabbed her by the shoulders and stared her straight in the eye. His expression was pleading.

"Please, Watson, this is something I have to do alone," he looked desperate, and despite her better judgement, Joan nodded her agreement.

He let go of her and started searching around for shirts. He found one and began dressing as fast as he could.

"Is there anything I can do?" Joan offered. She absolutely hated feeling useless.

He paused slightly, and then made his way towards the glowing vial. Ever so slowly he picked it up by a thin, black cord that was attached to the top. Joan hadn't noticed it was there before now, distracted by the luminosity of the contents.

"This is something which I lost," he whispered, "It is of great value to me and I need for it to be kept safe."

He offered it slowly to Joan.

"Will you wear it for me?" he asked, his voice gentler than she had ever heard it. It felt almost intimate as she reached out to take the vial.

Sherlock withdrew slightly and her hand lowered, somewhat worried and hurt that he had changed his mind. Instead, he took the cord in both hands and placed it softly over her head. The cord was long and the vial came to rest over her solar plexus.

"Are you going to be okay?" Joan asked quietly. There was an expression on his face which she had never seen before, and it scared her more than she would ever admit. He ignored her question completely.

"This vial," he told her sternly, "must not, in any circumstances, be opened."

"Sherlock," Joan started but he was already darting towards the door.

"Sherlock!" she insisted, running into the hall after him. He turned with his hand on the door handle. "What's going on?"

"Watson," he sighed, pain clear on his face, "I hope to God you never have to find out."

With that he turned and hurried out of the door, it closing behind him with a definitive thud.

Joan fiddled with the vial around her neck. It suddenly seemed to weigh a ton. She slid it inside her shirt so she couldn't see it anymore, but the glow shone straight through the material. She sighed and moved to the table, still cluttered with Sherlock's bits and pieces around the edges.

She sat down carefully on the edge of his chair and stared at his things, as though they would suddenly give her an answer as to what this little vial contained, and why it was important enough to warrant such a reaction in the man she had come to know so well.