Disclaimer: All this belongs to the BBC and I am just borrowing them from the sandbox. But oh, I don't want to put them back after this.

Ever wonder why the TARDIS was so accommodating to the Doctor? Why she accepted him when she was left in a scrap yard? How she got such a personality? My muse just came up with an idea.

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I'd just managed to get Luke to go out and take care of himself. I wasn't going to die in the next ten minutes or even the next ten hours. Of all the nasty things I'd fought over the years, the thing taking me away from life was so very mundane. Old age. My body simply couldn't keep going. It was almost annoying; after everything else, I was going out with a whimper, not a bang.

I was irrationally grateful that the doctor hadn't come recently (though I still worried about him). I didn't want his last memories of me to be like this.

Old.

Frail.

I nearly sent myself into a giggling fit when I thought about how poorly I'd thought of myself at the time when K9 and I ran into his tenth self. (I'd practically been a pin-up back then.) I restrained myself, conscious of the coughing fit that would follow.

A strange glow drew my attention and I stiffened. By god, it would be damned inconvenient if some old enemy came to... What? Have a giggle at the withered old crone on the bed?

"Hello, gorgeous," my onetime-friend-with-benefits said in complete honesty. Of course, almost everyone was a friend-with-benefits to Jack Harkness, so it didn't make me terribly special.

"You need to get your eyes checked," I shot back, but gave him a genuine smile. The fact was that Jack seemed more and more alien - if not physically, then mentally - every time I ran into him lately... So maybe his taste ran towards loose skin and white hair nowadays.

"You're always beautiful to us," Jack said with a smile. "I was wondering..." He paused for a moment, watching my expression. "... Would you like to see the Doctor again?"

"Oh…" I swallowed hard. "No. No, Jack. It wouldn't be good for either of us." I shook my head and tears fell. "He doesn't need to know my end, even if it's in a bed. I've enough vanity to prefer that he remember me the way I was."

Jack sighed sadly. "Silly girl. I wish you could see yourself as we do." His hand touched my hair and then my face felt so good that I couldn't help but lean into it. "But I never said he'd see you. Just that you'd see him."

"Oh." I chewed my lip for a moment, considering. To see him, but not touch him. Not talk to him.

"I never said you wouldn't touch him or talk to him," Jack answered my thoughts, and I glared up at him as he took my hands.

"Jack! Please stop talking in riddles," I growled and drew myself up, pinned him with one of my famous glares.

Jack chuckled. "Like you scare me." He rubbed my hands with his, futilely combating my poor circulation, trying to warm them up through paper-thin skin. "If you could be with the doctor, even if he'd likely never realize you were with him, would you? You'd be able to help him, protect him. You'd even be bonded with him."

"What are you on about?" My eyes never left him and I'm sure my expression was one of fear and hope mixed together.

"I found the TARDIS in the scrap yard. I was curious," Jack admitted.

I gasped. That meant he'd been to Gallifrey before the Doctor had left. As far as I knew, that shouldn't have been possible. Just how powerful had he become?

Jack didn't respond to me or my thoughts, only continued talking. "She was completely dead, Sarah. Completely, utterly dead. He'll never make it off Gallifrey in her."

"She was probably playing possum with you, Jack. You know how annoyed she gets with you at times and she's not bonded to the Doctor yet." I was grasping at straws and I knew it.

"Just like you get annoyed with me." Jack was looking at me with penetrating eyes.

"If you're trying to tell me I'm the TARDIS..." I made a point of laughing at him, but oh, there was hope building in my chest.

"Yes, I am." Jack was excited now. "The Doctor always said you were destined for great things."

"Well, I'd say saving the Earth umpteen times might be considered great in some circles," I quipped and arched my brow at him.

"Sarah, listen to me and tell me I'm wrong." Jack's voice turned serious. "You know how you and the Doctor could read each other? How you lost yourself when he left you behind?" He cupped my cheek. "How the TARDIS always liked you best? Of all his companions, you always saw the TARDIS as he did. Not just a ship, but a friend."

"But then I'd be a paradox, running into an earlier version of myself," I denied once more. The idea both scared the living daylights out of me and and made me want to leap in joy.

"The TARDIS whole existence is a paradox," Jack said with a chuckle. "And that's why it has to be now that you go."

I knew what he meant immediately. My story was done - at least as Sarah Jane Smith.

As the TARDIS, though...

"Luke..." I made one last protest before I gave in.

"Is a grown man," Jack countered deftly, "with a family of his own. He'll be without you soon enough, anyway, Sarah. And this way, you'd see him again."

"I can't just... leave..." I said desperately"

"Would you be able to go if you saw him again?" Jack asked. "If you go now, Luke will think the Doctor came for you. He'll be happy for you."

A tiny whimper escaped me. How could I just leave now? Not say goodbye?

"The Doctor needs you, Sarah Jane," Jack said with a tone of desperation in his voice. "If you don't go…"

He didn't need to finish. I knew what it would mean. "Why not Rose? Or…" Surely he could have reached her with the abilities he'd shown.

"She got Handy," he said with a grin, using the odd nickname that seemed to stick to the Doctor's clone in this universe. "This… This is yours, Sarah Jane Smith. You are the one he called his. Always his Sarah Jane, and he's yours. Always yours."

Yes, he would be. In a way no other companion would be able to take from me. It would always be me, caring for him, loving him, even if he didn't know it was I. I'd know when he needed me most, at least up to this point in time.

"Take me to Gallifrey," I said, giving into the inevitable. How could I possibly resist if Jack was right? How could I resist being with my Doctor, forever?

Jack's grin grew wider still as he scooped me up from the bed, then triggered his Vortex manipulator.

ΩΩ ΩΩ ΩΩ

I hadn't had long to get used to my new existence. It was incredible, really. I could feel time, sense it like the beat of my heart. It was exhilarating.

What was more exhilarating was when I felt him enter. His footsteps along my deck. "Come along, Susan," I heard him call to his granddaughter. I had only met this Doctor once, but oh, he was mine as well. They all were. They all would be.

"Well, now, let's see if this old girl is as anxious to get away from here as we are." I felt like singing as his hands touched my console, his mind reaching out to mine, and I welcomed him like the long-lost love he was.

Finis