Disclaimer: Nothing belongs to me.
A/N: This will only make sense if you are aware of the cast in all of the S4 episodes that have already been aired.

It’s been four years and she still calls the child her sister – at least when he’s around. It’s easier on both of them. She doesn’t think there’s a person in the world who could stand to see his face if she confirmed what they’ve both known all along, gave him such a wonderful gift only to snatch it away again when reality catches up with them seconds later.

Because really, who does that? “Hi. Nice to see you after all these years. I missed you. Oh, and by the way, you have a daughter you can never-ever see because if you try, two entire universes will almost certainly collapse. Bye, then!”

She can’t. She won’t break his hearts more than she already has.

It’s not easy, though. She’s positively aching to tell him once she finds him again, spends half their short time together biting her tongue when something reminds her of children or pregnancy or their beautiful daughter. She wants him to be proud of his little girl, to know that she’s starting asking about him, that she looks up at the sky every night before she goes to bed just in case he’s there, waiting for them in his magical blue box. She wants him to joke about beating up teenagers twice his size when they break his not-so-little girl’s hearts, to laugh with her at the inaccurate history documentaries her teachers tell her to watch, to show her the universe and let her fall in love with the stars just like her mother did.

In his life, though, between saving the world and almost dying and always running for your life, there is no room to even talk about children. There will never be a right moment to introduce a living, breathing one.

The universe saved, job done, and she still can’t bring herself to say the words he’s always known were waiting on the tip of her tongue.

One night, that’s all they have. After everything, that’s all the universe can give them. Any longer and the walls will start falling in on themselves. How can she drop a daughter in his lap one night and leave the next morning? It doesn’t matter how sure she is that he found her out a long, long time ago. They always were too good at sweeping things under the rug, and, in the same way she never forced an I love you from him because she knew it would be too hard, it’s kinder if she doesn’t have to say the words.

Lying across from her in the dark, he tells her about the Family, about how he punished them for his own revenge. She hates herself for keeping such a secret when he’s baring his soul so. There’s something in his eyes pleading with her to understand that he’d never have done it if she’d been there with him, but she’s not so sure. She saw him murder an entire race today. And though she can live with that, though she can love him with and despite the horrific things his very life forces him to do, she doesn’t ever want to make their daughter have to. Rose herself grew up with a perfectly preserved image of a prince of a father, and she could never find it within herself to take that away from her own child.

--

He’s not stupid. He knows, of course he does. He knew even when they said goodbye all that time ago, but perhaps the stupidest thing of all is how much easier it is to pretend he’ll never guess.

She doesn’t even have a picture.

Knowing their time is trickling away like sand between their grasping fingertips, he forgives her the lie, pushing away the fearful tickle at the back of his mind that sings he’d forgive her anything with or without the threat of separation hanging over them. He kisses away the tears as they roll down her cheeks, clutching her tighter than he’d like to admit. Perhaps if they try hard enough, they can pretend that hiding away in the TARDIS will make everything alright and that giant, threatening hole between their two separate worlds will just go away.

Neither of them sleep that night. He’s never believed in fairytales, and her heart’s too broken to try.

--

Here they are, then. Saying goodbye all over again on that damn beach.

I can’t stay, she’d sobbed the night before, unable to raise her eyes to his. There’s someone – they need me here. He’d looked on patiently, quietly, having suspected all along that this would be their end. Rose Tyler chose the universe over her own happiness the day she took that lever in Canary Wharf, and he doesn’t think he could love a woman who would abandon an entire universe, her own child, for a few snatched years of happiness and adventure with him.

Rose Tyler is not that woman. She never will be.

With Jackie gone and Pete with a job as the Head of Torchwood to return to, it’s the perfect excuse. She’d be needed even if she were just a sister.

His is no life for a child, they both know that. One hint from her and he’d give it all up in an instant, swap time and space and monsters and adventure for a little house with a mortgage and a white fence, watching his daughter grow young and Rose grow old, loving her for the rest of her life and longer. But she’ll never ask. She never could.

When he kisses her now, they both know it really is the last time. All that love and compassion and joy for life that she invested and recreated in him, everything that he’d forgotten how to feel when he lost her, is bundled up in a horrible knot that he seems to leave behind on her lips.

They need me.

But he doesn’t. Not anymore. That’s what she thinks, and she’s probably right. Oh, he wants her so much that it feels like he needs her, but functioning, breathing, starting to move on? She taught him how to live again. He can carry on living, for her, whether she is there or not.

The TARDIS is at his back. She used to be all he needed, all he even wanted. Now, Rose’s feet sink into the sand next to his and her tears fall blindly onto his collar. She can’t look at him, he can’t take his eyes off her, and he wonders how he ever got along without her. He doesn’t want to think about the state he might be in now if he’d never met her.

Their baby (he supposes he can’t call her that anymore, but she’s still so new to him) will do just fine without her daddy with a mother like Rose. More than fine; brilliantly, even. He knows that. If he had to leave a child with anyone, in either of their universes, he would without a doubt choose her. She’s strong and beautiful and full of a fierce loyalty that will never let anyone think badly of him for not being there. He, on the other hand… It’s been so long that, had he been faced with the reality of this life, he’d be terrified of messing it up. But that doesn’t mean he doesn’t want to rage at the universe for snatching away his chance to try.

“What’s her name?” he asks quietly, unable to suppress his curiosity any longer. He’s desperate to see her, to lay eyes on the most amazing thing anyone has ever done for him (she’s stronger than he thought, his Rose, carrying an alien baby all alone in a world that can never really be her home), to see whose nose she has, whose eyes, whose way of speaking. Maybe she’s clever, like him. Maybe she’s oh-so-human. Maybe she’s got two hearts.

He can never know. If he sees her, it will be impossible to ever bring himself to leave, and there’s another universe out there that needs him just as much as this one needs Rose.

She smiles softly through her tears and disentangles herself from him, the golden light of the sunset shining around her like she’s some sort of angel, a bringer of life.

What’s her name?

“Jenny,” she says, and turns and walks away.