Disclaimer: I don't own anything in the Who-verse. That honour belongs to RTD and the mighty and glorious BBC. The only thing I get out of this is a warm fuzzy feeling knowing I am trying to put right what once was wrong.

Author's Note: Thank you everyone for the phenomenal reviews. I just love reading them and replying to you all. This chapter is bit shorter than the last four monsters, but is significantly more fluffy than of late although with a sense of foreboding. Oh and in case you're wondering Siân is pronounced Sharn. I should have said last chapter. Mea Culpa. Anyway enjoy and please keep reviewing if you get chance. They make me so happy and are quite good at getting me past moments of writer's block. Wierd but true!

Chapter XVI

"What's this?" Donna called, waving a gaudily wrapped parcel in front of Jack's face.

Jack finished shrugging off his coat and hung it on the peg. He glanced at Donna and the parcel and then beyond her to the small figure of Siân who was bouncing up and down with the enthusiasm that only a three year old can display. As she met her father's eye he winked causing her to squeal in excitement and ran towards him to be swept up in a bear hug. Giggling she smacked a kiss on his chin.

"Ow! You're all prickly, Daddy," she complained her green eyes fixing Jack with a stare that left him in no doubt that she considered this a crime of the worst kind. Jack shifted Siân's weight to one arm and with his now free hand ruefully rubbed his chin.

"That's because Daddy get any sleep and hasn't had chance to shave yet," he said, adopting a grumpy tone.

"Why?" Ahh, the first why of the day. There would probably be a thousand more before bedtime. Jack grinned and kissed Siân on the nose, ignoring her wriggling attempt to avoid his stubble.

"Daddy had to work all night," he explained with a chuckle sending Donna an apologetic look. "Were you a good girl for Mummy?"

"Of course," Siân replied before Donna could speak.

Jack looked to Donna for confirmation who nodded with a knowing smile.

"Oh she went straight to sleep of course. It just took me forty minutes to drag her away from her book into bed...as usual." Donna ruffled her daughter's hair affectionately.

Jack rolled his eyes theatrically making Siân giggle again.

"And what book was it this time?"

"Five Go to Mystery Moor," Donna said. "Again."

Jack grinned. It hadn't taken very long before he and Donna had realised they had somehow produced a child prodigy. Walking unaided at ten months, talking at twelve, whilst other children Siân's age were still battling with their ABCs Siân was already reading books for children three times her age. And her abilities in writing and maths were equally as extraordinary. Donna had accepted it with a toss of her head and a barbed comment that she expected nothing less from her daughter, but her pride and wonderment were evident every time she watched Siân perform some miraculous new task.

Jack had questioned it. Of course he had. It was too much of a coincidence that Siâns' abilities had arisen by chance, given her parentage. He had tried to contact the Doctor, but since Siân's birth he had been keeping his distance. Flatly refusing to discuss how Donna could have known Ianto's grandmother's name, he had also been reticent to talk about Siâns' abilities. He had contented himself with saying that he couldn't see how Donna's buried knowledge could be passed on. That it could be something to do with Jack but, since Jack wasn't supposed to exist, there was no way he could guess what it might be. When Jack mentioned, somewhat pointedly, that none of his previous children had displayed such talents, the Doctor had merely waved his objections away. However to Jack's irritation his eyes had glittered telling Jack that, as always, he knew much more than he was saying. After several unsuccessful attempts to draw the Doctor out, a resigned Jack gave up and just accepted that his daughter was more special than anybody realised.

After Siân was born, Donna had stayed at home for a year, finishing her studies and enjoying the experience of motherhood, which she seemed to find effortless. For Jack, Torchwood had taken a back seat and he had cheerfully handed over the day to day running of the Hub to Martha and Gwen with stern instructions to contact him if there was anything more serious than a Weevil attack. He knew they'd ignored him as, on the grapevine came news of a failed Nostrovite incursion and a nasty little incident involving a flesh-eating virus of extraterrestrial origin. He didn't care. This time he was embracing fatherhood wholeheartedly. Taking dirty nappies (Donna refused to let him call them diapers) and midnight feeds in his stride. Donna laughingly called him a new man and was surprised and touched to see him colour up. The truth was Jack was a new man. He could imagine a future which wasn't filled with pain and, although he would always have regrets and secrets he could never share with Donna, for the first time he felt like he was in an honest relationship. Soon after Siân was born he had considered telling Donna about Alice, the daughter he had lost. He had asked Gwen, whether he should and she had looked at him in incredulity.

"You must be mad Jack!" she exploded, her Welsh accent becoming more pronounced as it always did when she was emotional. "If she finds out you've been keeping Alice's existence from her all this time, she'll be devastated. Not to mention that Alice and Donna are not that different in age. You'd have a hell of a job explaining that. Let it lie Jack."

"But I can't pretend I don't have another daughter." Jack protested.

"I know," Gwen said gently. "But Jack, all that telling Donna will do is hurt her and you. It's not like Alice is ever going to be part of your life again. I'm sorry Jack," she said seeing the pained look on his face, "but you know that it's true. For Donna's sake, leave Alice in the past. Just concentrate on your new family. The one's you can still help."

So he had taken Gwen's advice and stayed silent, burying the guilt he felt in denying Alice's and, by association, Steven's existence. And he tried to ignore the small but insistent voice in the back of his mind which reminded him that this new family couldn't last, that one day in the not too distant future, he would lose all of them too.

"Jack?" Donna said, startling him out of his thoughts. "The present?"

Jack focused on the box Donna was waving in front of him and with a smile lowered Siân down to the floor.

"It's for Siân," he said. "From a friend at work. He was sorry he'd missed her birthday last month." In actuality Jack had found the parcel on the front seat of the SUV earlier that day with a note, in a familiar hand, saying 'Whoops. Late again. Love to D & S x'

At his words Siân started to jump up and down excitedly her arms outstretched towards the parcel. With an indulgent smile Donna reached down and handed her the parcel. Turning on her heel she sped into the living room with Jack following closely behind. Sat on the floor in the middle of the room Siân ripped at the paper, scattering it, confetti-like, across the carpet. Jack sat down on the sofa and watched with interest as she pulled out a sturdy box with a picture of a microscope on the side. Jack raised his eyebrows. Clearly the Doctor was intent on expanding Siân's knowledge in the field of science. Siân's face lit up.

"A microscope Daddy. Can we get some soil from the garden to look at? Mummy says it's full of bugs too small to see called bacteria. Can we look now? Please Daddy?" She fluttered her eyelashes and turned her eyes to him pleadingly in a gesture she knew would have the maximum effect in getting her father to do what she wanted. Jack recognised it as one of his own.

"Isn't it time for nursery?" he said gently.

Siân looked at him in contempt. "It's Tuesday Daddy," she said in a tone of voice which told him, in no uncertain terms, that he should know better.

Jack held his hand up in defeat and resigned himself to not catching up on his sleep. "OK, bugs it is. Let me get that out of the box for you."

Siân bobbed impatiently at his side while he struggled with the packaging. He could put a Weevil down without a second thought, he grimaced, but faced with packaging on children's toys and he was as useless as any other parent. After several minutes he had finally freed the microscope which, although miniature in size, looked suspiciously well made and functional for a supposed children's toy. Switching the light on and looking down the eyepiece his suspicions were confirmed. If that was twenty-times magnification he was a Dutchman. The Doctor had had his hands on this, and one of those hands had definitely had a sonic screwdriver in it.

"Come on then," he said with mock reluctance. "Let's get soil."

Siân raced out of the door towards the kitchen and back door, and Jack followed with a yawn. It was going to be a long day.

Later that night as Jack came into the bedroom he found Donna sat, propped up against the pillows, her hair caught up in the student like topknot she liked to wear. Beside her on the bed were a pile of exercise books. She was frowning as she made occasional marks on each book in turn. Hearing him come in she looked up and smiled,

"I'm amazed you lasted this long. I thought you were going to fall asleep at the table tonight."

Jack yawned widely as he started to unbutton his shirt, "Who thought a teaspoon of dirt could hold so much."

"She certainly loves that microscope. I thought she was going to demand to take it to bed with her, but in the end she decided she couldn't abandon 'Monkey'."

Jack chuckled. " I find it quite comforting that in some things she's just like any other three year old. Sometimes she looks at me as if I have an IQ of 20. And my IQ is up there I'll have you know."

Donna looked at him in sympathy, "You're lucky. Sometimes I think she compares me unfavourably to an amoeba.

Donna looked at Jack as he took off his shirt his back to her, admiring his smooth back and well defined muscles. With a sigh she looked down at herself, she was in good shape, she looked after herself, but she could see it. Age creeping up on her, the laughter lines which seemed to deepen with every passing month, her skin which had lost that radiance it had had when she was young, the grey hairs which were now appearing with alarming regularity. Soon she would have to consider if she would need to colour her hair. She wasn't old, she was just...becoming middle aged. She looked enviously at Jack. He was older than her, by three years according to his birth certificate, but he didn't seem to have aged a day since they had met. No grey hairs, no wrinkles or sagging skin. He was still the Adonis she'd fallen in love with. She wondered, with a vague sense of unease, what Jack thought when he looked at her. Was he aware of the changes?

"What's the matter?"

Donna started to find Jack looking at her in amusement.

"Nothing," Donna said quickly, "Admiring your naked body."

Jack smirked and took a body-builder's pose.

"Eeew," Donna wrinkled her nose. "Never been keen on all that oiled musculature. Looks all wrong."

Jack's face fell and he allowed the pose to relax self-consciously.

"You are still so easy to wind up Jack Harkness," Donna giggled, reminding Jack of Siân sleeping not ten metres away.

"I'll get you for that," Jack promised with a wicked grin, leaping onto the bed and sending the exercise books flying.

"Jack!" Donna yelp scandalised, although he noticed that she quickly gathered up the books and put them on the floor out of harm's way.

Jack scooted under the covers and pulled Donna to him, nuzzling her neck along her hairline. She shivered

"I love this topknot thing," he murmured as he pressed soft kisses onto her exposed sensitised skin, then he lifted one hand and released her hair so it fell down over his head like a curtain. Donna shuddered as Jack continued he exploration of her neck under the hair. Finally he pulled his head back and started to nuzzle the front of her neck under her chin.

"Jack," Donna moaned.

"Sush! Busy," he said into her neck, his lips tickling her skin. Then he pulled her down from the pillow so she was lying beside him.

"Siân's obsession with looking at things in more detail gave me an idea," he said slowly, his words punctuated with kisses. "I thought I might spend the evening looking at you in more detail."

"I thought you were tired," Donna managed to splutter as Jack proceeded to turn his not inconsiderable attentions to her collar bone.

"Curiously not," he said softly raising his head to look at her, his blue eyes vivid and dancing with mischief. He allowed his fingers to trail down her stomach where Donna knew the scar of her operation was still visible. Unconsciously she tensed. Jack felt it and sighed inwardly. Ever since Siân's birth, Donna had been self-concious about the scar on her stomach, at first forbidding Jack to touch it, or even look at it, saying that it was ugly. It had all of Jack's considerable talents to persuade her that to him the scar was beautiful, a sign of what she had been prepared to sacrifice for him. But even now it was if, every time he touched it, she was having to face a fresh hurdle. He understood, but he wished it wasn't so.

"Donna," he said softly, "Relax." He followed the words with a long deep kiss, claiming her mouth, his tongue insistent between her lips until he felt her muscles relax and she let out a smothered moan against his lips. Donna wrapped her arms around him, anchoring him to her. Jack chuckled against her lips.

"Patience woman," he muttered, breaking the kiss and allowing his lips to follow the path his fingers had taken. With the small part of her brain that was still functioning, Donna wondered idly whether all couples approaching their fifth anniversary felt like this, and whether the wicked things Jack was doing with his tongue were actually legal.

Much, much later as Jack lay dozing, his head on Donna's stomach, Donna stoked his hair and asked, wistfully,

"Do you ever get grey hairs Jack?"

Jack was instantly fully awake, his stomach churning. "Of course," he assured her. "You know how vain I am, I pluck them out before anyone can see them." He tried to keep his voice deliberately light.

Donna snorted, "If I did that I'd be bald in three months."

"Rubbish." Jack scoffed. "You look exactly the same as when I met you." As soon as he said it, he knew he'd made a mistake. Donna had changed, motherhood, time, teaching, they had all left their mark on her face but this did not detract from her beauty. It had only enhanced it, her face full of life and character and above all confidence.

"You're full of crap, Jack Harkness," she replied without rancour. "I'm getting old and wrinkly. Before you know it my boobs will be round my ankles. Then what will you do."

"Spend a lot more time on them," he said flippantly casting a suggestive leer up at her.

Donna laughed, "No, but honestly Jack. You haven't aged a day since I met you. There might be an odd grey hair but I've never seen one, and I haven't found one wrinkle – and believe me I've looked. How do you do that?"

Jack's stomach lurched again, hollowly remembering Gwen's warning as he replied, "Good genes."

"Yeah, well I wish I had them," Donna quipped running her fingertips over Jack's face.

"I'd say your genes are pretty fantastic," Jack said playfully, willing the sick feeling in his stomach to go away. "You're just fishing for compliments, Mrs Harkness," he continued.

"Absolutely," Donna agreed. "So go on, compliment me." She wriggled her bottom suggestively.

"As you wish," he replied turning his head and flicking his tongue into her bellybutton. "Fabulous bellybutton," he murmured, "Superb stomach, flat but with a hint of softness. Shall I go on?"

All Donna could do was nod.

Jack watched as dawn lightened the sky outside the curtains, listening to Donna's slow even breathing beside him. He hadn't slept. His mind had churned, over and over, relieving the conversation. It had been a joke, just foreplay. He knew that. But how long would it be before those light-hearted observations became genuine curiosity. How long before his immortality became the trigger that would open the dam in Donna's mind, taking her from him...and Siân. Something that couldn't be allowed to happen. How long did he have before he had to leave them behind, for her own good. Because one thing was obvious after tonight. He was living on borrowed time.