Mary is baking gingerbread men.
She learned how when she was hiding out in a Chicago bakery after the assassination of a politician, and she's been making them ever since.
The icing recipe, Italian, was picked up in Naples from the kindly cook of a wealthy landowner who met his end two weeks later in a tragic car accident.
She runs the decorated roller across the dough making patterns. A tradition that goes back even further to the pryaniki that her grandmother used to bake when she was a child. One of the few childhood memories that she allows herself to keep.
Then she picks up one that has cooled, one wearing a bow tie, and she paints on a bright red smile.
John enters the flat then and smiles at her. He wipes flour off of her nose before kissing it. Then he turns her more fully toward him and kisses her more deeply. She laughs, and he smiles back at her.
"Baking again I see? What are you making?"
"Gingerbread men."
He looks at the array of gingerbread figures that are decorated with coats and hats and jumpers.
"You make them so perfectly, how can I possibly eat them? Oh, is that one a soldier?"
"Yes."
"And that one, he's wearing a long coat like Sherlock's."
"Is he? I hadn't noticed the resemblance."
"Honestly, it looks just like him."
"Hmmm."
"Well, I'm off to bathe and then bed. You coming?"
"In a bit. I have another batch to put in the oven. I thought I'd give them to the girls in the surgery."
"Wonderful. Don't be long love," he said giving her a hug before leaving the kitchen.
She puts the soldier and the others onto a cookie sheet, and slides them into the oven. Then she lifts her finger and licks the tip.
Mmmm, sweet.
She knows that she really shouldn't be doing this. The wedding is still months away, and Sherlock is back. He or John might recognize these as similar to the ones that she baked for Jim all those years ago. A sorry batch that he'd insisted she burn.
It's a dangerous tell, but old traditions die hard, and Christmas traditions die even harder.
She picks up the figure in the coat and bounces it across the table singing...
"I run and I run as fast as I can. You can't catch me, I'm the gingerbread man!"
Then she bites his head off and chews, savoring the honey sweet taste of ginger and treacle.
She bakes gingerbread men every Christmas to remind herself of one simple fact. The way to survive is not to be the one running. The way to survive is to be the fox.