"Sarah Jane."

She looked up from her book in surprise. "Do you have that analysis already, Mr. Smith?"

"No, Sarah Jane. However, there is a spike in --"

" --sufferable immortal ASS into next..."

Sarah Jane jumped up and spun round at the woman's voice where no woman had been a moment before. There was now, dark eyes perfectly round, mouth hanging open, curls raked back into a ponytail as careless as the grey pullover and jeans with a scorched streak down one leg.

Twice the age she should be, three inches too tall, and on the wrong side of the Atlantic.

"Sarah Jane?" Maria breathed. Just for a second longer, she looked as if she'd seen a ghost. Just long enough to wonder if perhaps she had. Then a broad, brilliant smile split her face, and she rushed round the chair to capture Sarah Jane in a ferocious hug. "Oh, I am going to kill him!" she crowed, the obvious delight in her voice completely at odds with the words. "Twice! Maybe three times."

She let herself indulge in the hug for a few seconds, then took Maria firmly by the shoulders and pushed her to arm's length. "Maria, what... Where did you come from? Are you in trouble?"

A dozen different answers flickered behind the young woman's eyes, none of them the one that emerged from a suddenly-more-guarded smile. "Nothing out of the ordinary. Oi, unless -- I'm not going to come through that door any minute, am I?" She tapped at the device strapped to her wrist and frowned. "Oh, look, it's dead. Again. Why am I not surprised?"

"It's 2008." Sarah Jane pushed her voice past a lump in her throat. "Christmas. You needn't worry about meeting yourself."

"Well, at least he can get that much right," Maria muttered. "But really, Christmas? I am going to kill him."

"Kill whom?"

"Bet you could guess." The tilt of her head was entirely Maria, but she was so tall, and confident, and heartskippingly beautiful. "Captain Jack 'God's-gift-to-sentient-beings' Harkness, of course." That indignant little choking noise, that hadn't changed. "And before you ask, absolutely not!"

"Before I ask...? Oh! No, I wasn't thinking... Maria!"

"Sorry. You get so used to people making assumptions, and it's been so long since... Never mind."

"You want to say more." Sarah Jane stated the obvious, for lack of anything else to say. "But you can't, can you?"

"Sorry," Maria repeated. "Mr. Smith?"

"Yes, Maria." The computer had made no comment about her presence, and now answered her promptly.

She held up her wrist toward him. "The vortex manipulator. I think it's just the power cell discharged again, but can you scan it and make sure?"

"Of course I can. Please place it in the slot." She complied, and a moment later Mr. Smith announced, "You are correct, Maria. It should function properly when the power is restored."

"Thanks, Mr. Smith."

"You are very welcome, Maria." As she took it and strapped it back on her wrist, Mr. Smith commented, "That vortex manipulator has been modified from its original design."

Maria grinned. "Couple of times. Good job it has, too. Means I can catch the next train to Cardiff, charge it up on the rift, and make it home for tea. With time to spare for kicking Jack's --"

"Maria!" The exclamation was automatic, ludicrous as it was to address it to a grown woman.

The visitor just smiled. "I miss that," she admitted. "Sometimes I think what we really need is a mum about the place."

That lump in her throat was back, more insistent now. So many questions she wanted to ask, and didn't dare. "Is it... very bad? What can I do?"

"You've done it." Maria hugged her again, tightly. "I wish I could stay, even for a little while. But they need me. Even if the knight in shining tooth-polish has other ideas."

"Too right they do." She pulled back, but Sarah Jane took her face in both hands. "I am so, so proud of you. You remember that."

"Always do," Maria whispered. "Always will."

"Mum!" Luke's shout preceded him up the stairs, and he burst into the room, continuing, "Phone! It's -- " He stopped in his tracks. "Maria?"

"You are correct, Luke," Mr. Smith put in helpfully.

Sarah Jane swallowed hard, swiping impatiently at the tears gathering at the corners of her eyes. "You two go downstairs. She'll explain." When he didn't move, Sarah Jane prompted, "Luke? The phone?"

"Oh. Sorry." He handed it over, never taking his eyes off the grownup Maria standing unexpectedly in his house.

Maria put her finger to her lips and gestured to him to lead the way. She tossed a wistful smile over her shoulder at Sarah Jane, then followed him down.

"Hello?" the phone in her hand asked tinnily. "Luke? Are you there?"

"Hello, Maria. He's handed it off to me."

"Sarah Jane!" Maria's bright young voice burst from the receiver, all energy and promise. "You're not crying?"

"Holiday films," Sarah Jane scoffed. "Isn't it rubbish, how they get you every time? But never mind that. I want to hear all about your first American Christmas."