Sherlock was waiting in the kitchen when Jessica ambled down the stairs, tightening the drawstring on the shorts. Even the shirt that had shrunk to squeeze Sherlock's frame hung loose on Jessica, even if it hadn't been because she was thin.

"Are you ready for your next experiment?" he asked from the stove, stirring the warming milk to keep it from developing that nasty pudding-skin that Sherlock hated so much.

Jessica leaped into he same chair as she had before, wet hair dripping onto the linoleum as she earnestly nodded her head. She was a very quiet girl - Sherlock wasn't sure if he liked that or not at the moment.

He nodded regardless. "Good. This -" He deftly poured the warm milk into two mugs and stirred cocoa powder into each of them. "- is your next assignment. How long will it take for this to be cool enough to drink? Sip carefully and tell me when you're certain; I'm parched." Then he sat back, folded his hands neatly over his chest, and closed his eyes, listening to Jessica tentatively slurp at the warm drink.

He waited four minutes before she put down her mug and announced, "Okay, it's cooled off now!" before returning to the drink with gusto. She'd finished before he had even gone halfway through his, and he made a mental note to make sure she didn't get sick or shaky from too much sugar.

To: John
Stop for chocolate milk and fish fingers on your way home. SH

From: John
Chocolate milk? Why chocolate?

To: John
Experiment. SH

To: John
Also, custard. SH

"Well, that's all the experiments I have for now," he announced after he'd switched his mobile off and stowed it away in his pocket. "You have leisure time to do with as you please."

Jessica looked almost disappointed. "Does that mean I have to go?" she asked in a small voice. Sherlock felt a different sort of tightening in his chest than before when he'd made her laugh.

"No, I already said you didn't," he sighed. "Another experiment may come up later that I'll need your express assistance on. In fact, while I'm thinking of it, go study the number of credible plot devices in Doctor Who while I do some chemistry out here."

He shooed her into the sitting room, pressing the remote control into her hand, then began scrounging in the cupboards. Eyes narrowed with concentration, he pulled out a jar of peanut butter and loaf of bread, and set to work making toast with ill-practiced hands. He didn't usually make food - typically, that was John's duty, and Sherlock simply didn't eat when he was out playing doctor - but he supposed this would be an opportune time to learn. As he worked, he watched Jessica stare rapt at the telly screen, occasionally shouting instructions to the man in the bow-tie onscreen or laughing.

There it was again, the warm tightness that had gone cold when Jessica thought she had to leave. Why had he reacted in such a way to that, to how forlorn she'd sounded? He didn't even know this girl two hours ago, and now he was making her toast and letting her watch John's television. It hadn't been because she looked hungry or sad, either.

"How's your studying faring?" he asked, sitting beside Jessica on the sofa and handing her the plate of toast. When she eyed it skeptically he set her with a stern gaze. "Scientists have to eat, especially peanut butter."

"Why peanut butter?"

"Because it's delicious, of course. I expect at least half of this toast to mysteriously disappear by the time I next look at that plate," said Sherlock, and then turned resolutely to the television. "What's going on here?" he asked after several minutes of listening to her munch on the toast. "I don't understand the point of this program at all."

A blatant lie; John and Mycroft were the only people who knew that Doctor Who was the one constant popular culture program Sherlock would ever follow, and the only one to constantly surprise him.

Jessica put down her toast and straightened authoritatively in her seat. "There are Cybermen in the shop, and the Doctor's supposed to die, but first he has to say goodbye to Craig, and he explodes the Cybermen with love," she explained in one breath, never tearing her eyes away from the screen.

"He blew them up with love?" asked Sherlock suspiciously. "That's illogical."

Practically vibrating off the sofa with enthusiasm, Jessica stood up on the cushion so her feet sank slightly, bouncing slightly. "No it isn't! See, Craig - he's the Doctor's friend - Craig was being turned into a Cyberman but then he heard Stormy - that's Alfie - that's Craig's baby - he was crying because he was with Val - she thinks the Doctor and Craig are Stormy - Alfie's daddies - and then the Doctor saw Amy and Rory - they were his companions but then they weren't - and then also River - she's - wait..." She trailed off, confused by her own commentary, and Sherlock laughed.

"Why don't you show me?" he suggested when she sat back down, looking petulant. "I practical demonstration might help. You be Craig and I'll be the Cybermen."

Her eyes lit up. "Okay! Wait, we need a Cyberhead to stick on Craig, and a baby Alfie!" Without waiting for him, Jessica streaked into the kitchen and emerged with a bowl, then took up the union jack cushion John was partial to. "This is Alfie, okay? He's over here in the shop with Val." She dropped the improvised baby into Sherlock's chair, then scuttled back over to the sofa and handed Sherlock the bowl. "This is the Cyberhelmet. You have to try and get it on my head, okay? And I'm gonna try to get away, but then - well, just wait and you'll see. Try to get it on my head!"

Sherlock dutifully raised the bowl and mechanically moved to bring it toward her face. He cleared his throat before speaking. "You will lead us," he said in perfect imitation of a Cybervoice that made Jessica's eyes go wide. "You must be upgraded."

As the bowl moved closer to her face, Jessica struggled against invisible bonds holding her to the sofa. "No! No!" she wailed theatrically - Sherlock could see a great career in dramatics ahead for her. "Alfie needs me! Please! Doctor, help, help!"

"Your emotions will be eradicated."

With one last pitiful whimper, Jessica allowed Sherlock to put the bowl over her face and went still. He waited several moments, wondering what she was going to do next, and she pulled her head back enough to free her mouth. "This is the part where Stormy - Alfie - is crying, okay? But you have to say the last bit about 'conversion complete'."

He nodded gravely. "Alright. Conversion complete."

"Good, now Alfie's crying."

"Okay."

Jessica tucked her head back into the bowl, was still for several moments, and then quietly jerked her shoulders and raised her arms quickly enough to dislodge Sherlock's and rip the bowl away from her face with a shout. "Alfie!" she cried, jumping off the sofa and lovingly pulling the cushion into her arms. She glanced at Sherlock from the corner of her eyes and tisked at him. "You have to blow up now, because I blew you up with love."

He raised his eyebrows. "Oh, right, sorry." Then he made an exploding gesture with his hands and flopped over onto his side, slid off the cough, and fell to the carpet, unmoving. Jessica giggled; he slid one eye open a fraction. "Was that acceptable?"

"Mm-hm."

Sherlock sat up but remained on the floor. "Good. I think I have a better grasp of it now; thank you. May I see Alfie?"

"He prefers to be called Stormaggedon: Dark Lord of All," supplemented the girl, crossing the sitting room and placing her baby into Sherlock's arms.

Before she could step away he tugged the hem of her - his - shirt, pulling her in to sit on his leg. She giggled. "Now," he said seriously, "I believe we have to do a thorough eye-exam on you before we do another experiment, because this so-called baby looks like a cushion to me. Here, look closer!" And then he popped her in the face with the union jack; she shrieked and leaped away to grab her own cushion.

Leaping to his feet, Sherlock arranged himself into a comically-defensive position while Jessica ran toward him. He swung his hand back widely and slowly, allowing her to make a blow for his stomach and doubling over. "Oh, you got me a good one!" he groaned, and Jessica laughed before hitting him on the head. "Oy! You've already gotten me; that's just rude!"

As he sat up Jessica leaped back, still clutching her pillow as she grinned. "Well you gotta get up faster!" she protested gleefully.

"Faster, you say?" he asked shrewdly, and leaped to his feet in the blink of an eye, wielding his cushion high over his head. Seeing as he veritably loomed over her, Jessica shrieked with laughter and ran clear across the flat into the kitchen to escape him.