It was the flash of lime green that caught his eye- a contrast against all the dull grey concrete buildings and the dull pale snow that had fallen last night. The bright color drew his attention for a brief second before his gaze wandered critically onto the rest of the mundane London cityscape. It was barely long enough to register the image of a long wind-tugged lime scarf lazily floating behind its owner down the street. He walked on. The scarf passed by and disappeared, replaced by the more ordinary dark woolen winter garments of the very few other pedestrians who were walking London's streets early on Christmas morning.

Sherlock was on his way to St. Bart's morgue, for no other reason than to maybe see if he could sneak some body parts back to 221B Baker Street. For experimental purposes, he would say to Molly, and then probably compliment her hair again or something stupid like that. Really, though, he just needed something to do before he died from boredom. John had insisted on spending the day with Sarah instead of tagging along with Sherlock on whatever new case Lestrade was sure to have. Then Lestrade had finally answered his texts with a weary phone call saying, no, Sherlock, there is no new case, for god's sake go and have a nice Christmas with your family, or whatever. Which of course was impossible, because family was Mycroft, and Sherlock would rather spend the day tromping sulkily through the snow and dissecting fingers than attend one of Mycroft's horrid social gatherings.

Sherlock always compared a good murder case to Christmas-come-early, but in reality Christmas wasn't exactly his favorite time of the year. So here he was, alone and irritated. And cold, not that temperature was ever anything but a mild inconvenience for him. Sherlock drew his own scarf tighter about his neck, idly thinking what a garish shade of green the other had been. Reminded him of something.

His phone buzzed at the bottom of his coat pocket. Sherlock, gritting his teeth, stopped to text Mycroft back yet another scathing reply to his continuous messages of fake holiday good will.

The flash of lime flickered into his peripheral vision again, and stayed there.

Sherlock paused and frowned. Green Scarf had passed by nearly a minute ago, on the other side of the street, heading in the opposite direction. Unless two people had the exact same article of clothing, Green Scarf had doubled back on its route and was now stopped exactly one street-width across from him.

Sherlock looked up.

Jim Moriarty was leaning against a building across the street, the lime green scarf looped around his scrawny neck. He was looking directly at Sherlock.

Brown overcoat, hands in pockets.

Designer jeans, soggy at the ankle from the wet snow.

Sherlock dropped his head back down to his phone—or at least he pretended to, while surreptitiously checking his chest for red laser dots. None were there. He looked back up and met Moriarty's gaze calmly.

The green scarf fluttered and beckoned.

Sherlock stepped off the sidewalk and crossed the snow-dusted street.

"Hi," said Jim.

Eyes still tired, but sharp as a needle.

Mouth twisted in happy amusement.

Sherlock said nothing and looked at him expressionlessly.

"I was wondering how long it would take for you to notice me," said Moriarty. "Here I am going to the store, and who do I see but Sherlock Holmes on the other side of the street. Thought you'd spot me for sure. And then you just walked by without even looking at my face! Ouch."

Sherlock raised his eyebrows and said nothing. Moriarty grinned, Cheshire-like.

"Nice scarf," remarked Sherlock.

"Really, you think so?" He sounded pleased.

"No."

"Bought it just yesterday. Christmas gift for myself. Merry Christmas, by the way."

"What do you want?" asked Sherlock curtly.

Moriarty turned his head to the side, seemingly contemplating the pale sky. "Well, to tell the truth, I was sort of hoping for a particular Greuze that I've had my eye on. But I can always buy it for myself later. My employees did give me some very generous presents, so I shouldn't complain."

Sherlock watched him.

"Probably bribes, actually," added Moriarty after a moment, turning back to Sherlock with a shrug. "In any case, I'm in a good mood."

"You wouldn't confront me unless you had your little band of snipers to protect you," said Sherlock. "So where are they? Are you saving them for later?"

"I told you," replied Moriarty with a touch of annoyance. "This isn't a confrontation. I really was just walking to the store. I'm running low on produce and hot cocoa."

"Do you really expect me to believe that?"

"Not everything's about you, Sherlock, m' dear." Moriarty winked and put a finger over his lips in a 'shushing' gesture. "I noticed something interesting just a few blocks back. Wanna see?"

The criminal mastermind turned on his heel and began walking up the street again, towards Bart's. Sherlock stayed where he was.

"Come on, then," called Jim.

Sherlock looked around. The area was deserted, except for a single car which drove past and disappeared around a corner.

He made up his mind, and followed Moriarty.