AN: This update is care of a prompt on tumblr after I complained of needing fluff ideas because I didn't want to write anything difficult. This is the result of someone suggesting babysitting. The baby in this story also makes an appearance in Full Circle as a toddler.

Jem heard the door open and smiled but didn't stop playing. He was drifting in the music today. It filled the little apartment and reminded him of the way the house had felt when his parents had played. Some days music was just sounds. Some days music was magic. Today it was magic.

He was playing old pieces. Songs his father had known by heart, some of which he could only find the names of by listening to hours of clips on the internet. Today it was one of Bach's more obscure sonatas that his father had adored but few other people could even identify.

As the last notes faded he finally turned to see Tessa standing in the kitchen. Her London apartment was small but beautiful and situated above a bookshop she also owned. Unlike the house in LA or the apartments in New York and Shanghai this was not a space that was theirs. It was a place that was hers. She shared it with him but it wasn't his. Whether in spite of or because of that it was one of his favourite places in the world.

It was the first place she had taken him after he had found her again on Blackfriar's Bridge. That might have been part of the reason that he loved it so very much. It was a place full of memories, all of them good.

She stood in the kitchen in a sundress and a pair of sandals with a contraption resting on the floor by her feet. She also had a large bag slung over one shoulder. He tried to remember what she had said she was going to do when she had left. He frowned at the entire ensemble. Even though he had already pulled out the violin he was certain she had said she was going to run an errand for a friend.

"What's that?" he asked.

"A bassinet," she said.

"Which is a thing to carry babies," he said.

"Yes," she said.

"Does it have a baby inside?" he asked.

"Yes," she said.

The strange fluttering emotion in his chest settled back into confusion. It had been somewhere between terror and elation a moment before as he had tried to play through the reasons she might have brought a bassinet home without warning him first.

"Did you pick up a baby while you were down at the shops?" he asked. "Were they on special?"

Tessa laughed and grinned at him, "I don't think they sell babies in shops. It's fairly illegal to purchase people in this country. Magnus and Alec are watching over this little one while they try to find her mother. They needed a break. Neither of them have any idea what to do with a child. It's sweet but I think they needed a little bit of time to relax."

"So you stole a baby?" Jem asked.

"Borrowed with permission," Tessa corrected.

He put down the instrument and came over to look at the bassinet at Tessa's feet. She picked it up and put it on the kitchen counter. Inside was a very blue little face wrapped in a white and green knit blanket. The child had a shock of black hair on her head and her ears were too large and too pointed to pass as human. One of her tiny hands was curled into a half fist beside her face. She was fast asleep.

"What's her name?" he asked still staring at her. He had known about the baby that had been found and had known the child was a warlock. He hadn't thought much of it before but he'd never seen a warlock infant. Not in all his time in the Silent City had he ever seen a warlock as a child. It seemed strange to him to imagine warlocks as children. He took a moment and tried to picture Ragnor Fell or Magnus as babies and couldn't do it. Warlocks were complete and fully grown.

"She doesn't have one yet," Tessa said. "Whoever left her didn't leave a note and no one wants to name her before they've found her a permanent home."

Jem reached out and touched her hand and she twitched her fingers, "I didn't know babies were so small."

"You've seen babies before, you've held babies before, this one is a little bluer but not that much different from a Shadowhunter baby," Tessa said shaking her head at him.

"Never as myself," Jem said. He was still touching the child's hand as he tried to explain. It didn't quite make sense to him but he wanted her to understand it. He paused and then said, "I've never held a baby as myself. Brother Zachariah helped deliver babies and was a doctor for small children and spent time with Jamie and Lucie but I - me, just Jem - I don't really know any babies. Not before. Not since."

Tessa leaned into him when she reached out to pick up the baby out of the nest of blankets. The little blue girl blinked a few times and Jem caught sight of bright pale blue eyes before she yawned and settled back to sleep in Tessa's arms. Jem's heart did strange things as he watched Tessa's face as she smiled down at the little girl who wore a onesie with ducklings printed on it.

"I am now going to hand you this child," Tessa said. Jem drew back but didn't step back. The girl was asleep, peaceful and vulnerable and so small that he was intimidated by the very idea of touching her. Tessa stepped into his personal space with the baby in her arms and flashed him a smile. That terrified elation came roaring back as he tried not to think too much about the possibility of there being a child someday that was theirs and not just borrowed.

He let her place the little bundle in his arms and tried to remember how to handle a baby. Babies usually cried when handed to Silent Brothers and Jem was a little startled when she did no more than open her eyes briefly and wave a tiny fist at him before falling asleep again.

"This baby sleeps like a rock. She should give lessons to all the other babies," Tessa said and then stepped in a little closer to him to adjust his hands, "Stop holding her like an egg. Keep her head there but hold her securely, keep her close, she should feel safe with you."

Jem turned his attention to Tessa who was looking down at the tiny sleeping baby between them. Her hand was on his arm and he relaxed a little then a little more as Tessa touched the girl's cheek and her hair and her tiny hands. He wasn't sure which was more fascinating, the tiny warlock or the way Tessa fussed over her.

When the baby opened her eyes and twisted in Jem's arms he readjusted her without Tessa needing to tell him to. She stared at him with those ice blue eyes and Jem grinned at the force of personality in that look. She made a noise that Jem imagined was a happy one as she looked at him as though appraising this stranger looming over her. She waved her tiny hands and caught one of Tessa's fingers in a fist and drew it down to stick in her mouth.

"If she needs someplace to stay," Jem said, "She could stay with us for a little while."

"Magnus hasn't admitted it yet but there is no way he's letting her stay with anyone else, not even you and I," Tessa said.

"But she can come back to visit," Jem said and Tessa nodded at him. She flashed him another smile and he realized that she had that same terrified and elated thought that he had had earlier. It stayed silent as they spent the afternoon passing the nameless baby back and forth until Magnus came to collect her and take her home.