A/N: This is the final instalment. And epilogue of sorts, to make sure the pieces all fit together nicely. Thank you very much for reading and letting me share this with you, it's been a whole lot of fun to write.

Your feedback is golden!

Enjoy

"Alright, spill."

Nothing like being back on the TARDIS with Amy and Rory. Nothing like being whined at by one companion and interrogated by the other. Well, it wasn't exactly his fault that he forgot about Rory a little bit while he took Rose home. It was Rose. Besides, thinking about Rory was Amy's job.

"It's a long story," he said and the second he said it, he regretted it. Amy was all fire and red hair, staring him down like he was a bad puppy.

"We can stay in the vortex till the end of time if you like," she said. "Spill!"

She looked frightfully serious. Oh dear. "What was the bit with the necklace?"

Ah. A starting point. Thank you, Pond.

"It's actually fairly amazing," The Doctor said, still a little giddy. "Even for me. It's a time paradox. You see, the first time I ever saw that necklace, Rose was nineteen and she told me that she'd had it since she was seven. Didn't remember getting it, but there it was. Her mum thought she had stolen it because it had these letters on it see, but the letters weren't what she thought, they were…"

Ooh, Bad Wolf. Right. Not essential information.

"…they were…just there. Anyway, Rose leaves, necklace stays on the TARDIS, Doctor finds necklace. Doctor locks necklace away till Rose comes back, but Rose doesn't find it, other Doctor does."

Till Rose comes back…not that he ever thought she would. Had never even let himself hope, and yet she was there that day. That day with the ghost town and Donna and Jack and the Daleks. She crossed time and space and realities to find him again. And he had let her go.

"What other Doctor?"

Oops.

"Er…did I say…never mind. Other person finds it, but forgets it and ends back in Doctor's hands again. Cue paradox. The necklace was never made, see. The Analysis pan said so. Remember the little camper van pan? With the rust and the…? Anyway, the necklace. Never been made. But at the time, I didn't understand, of course, because how can something never be made? It's impossible."

"Except that it isn't."

"And you're catching on, Pond!" He grinned.

"Well, I'm not. It isn't what? What?"

The Doctor sighed. Rory Williams was ruining his flow.

"It's a Moebius Strip. The start and the end of the timeline of the necklace are essentially the same place, and so it creates a big old time loop."

"What?"

"Why don't people study recreational mathematics anymore?"

The Doctor skipped to the console, picked up a piece of paper and tore it into a nice strip. He scrunched the other part into a ball and threw it at Rory's head.

"Oi"

"Sorry, couldn't resist."

He held up the piece of paper. "Ok. Imagine this piece of paper is time. The start of time, or at least, the start of this particular timeline is the day little Rose Tyler gets a necklace from a random but handsome stranger. Hoorah, free gifts and celebrations. Go along the line and you have Rose Tyler, all grown up, and her Doctor, on New Earth on the grass, talking about her necklace –"

"Her Doctor?"

Oops.

"Go along the line and Rose Tyler is gone and I find her necklace, still on the TARDIS."

"Where did she go?" The voice was warm and concerned and sympathetic and Amy Pond all-over.

"Keep going along the line and she comes back, cue her room re-opening, cue her necklace being found again." Ignoring unessential, painful questions was really the only way to proceed. How on earth was he supposed to explain paradoxes if he kept getting sympathetic looks?

"And that was by who?" Rory Williams. Less sympathetic. More blunt. Like a truck.

"It's whom," The Doctor corrected. "And that's not important. What is important is that the necklace was back in my hands."

"With the note."

"Yes Rory, with the note. You were there, I was there, it was all very special. Moving on down the line, the three of us arrive in 1993 and I give Rose Tyler a necklace." He tapped the last end of the strip of paper, looking at his companions expectantly.

"The last event is the same as the first."

There we go. Rory Pond was finally catching up.

"Exactly!" He folded the paper over so that it made a circle. "Moebius strip! See? First and last events create a loop. A great big, wibbly wobbly, never-ending loop. Cue paradox!"

He grinned. Amy and Rory looked at him, wide eyed and empty. Humans. Did he have to explain everything?

"That necklace only exists within those years. I gave it to her in 1993, she left it for me in 2006, The meta-crisis found it in 2008 and Amy found it in 2011."

"Right…"

"What's a meta-crisis?"

Enough, already! "That's…too confusing to explain and not at all important right now. The question is, where is the necklace now?" The Doctor asked, ignoring them again.

Rory looked non-plussed. "In 1993," he said. "You just gave it to her."

"Exactly!" The Doctor said with a little jump. "So, in 2011, where is it?"

"It…it doesn't exist…"

"Yes! It existed in 1993 because I gave it to Rose and it ceased to exist in 2011 when we left the Paradise Planet of Parklah to see Take That in 1993, which by the way, starts in two hours so we'd better make this quick! Outside that time frame, it doesn't exist. It exists because she left it for me, but she only had it because I gave it to her. That's why it gave me the tingles. My superior Time Lord senses recognized that it didn't belong, that it wasn't right. It was never made. Brilliant!"

Amy was grinning. Rory was smiling slowly. Yes, they were with him. Ha ha!

"Come on, though. Isn't it brilliant?" he kept on, unable to help himself. Rose Tyler. Still amazing him. "A necklace, a tiny insignificant necklace defying time and space!" The Bad Wolf, once again proving to him that she was brought to him by fate. That they had been bound together her entire life.

And now Rory and Amy were staring at him. With that look. That knowing look. He hated that look.

"Who was she?"

He hated that question.

She was Rose Tyler. She was the Bad Wolf, created by time and space and the vortex and the TARDIS and Jackie and Pete Tyler. She was sent to him to save him. To save his life and then his soul, and then his life again, many times over. She was the saviour of his ninth existence and the reason for his tenth. She was generosity and curiosity and warmth and fire and golden, bright light. She was goddess eternal and fragile rose. She was…

"She was the stuff of legends."

Four hours later and twelve years before, a little blonde girl lay in her bed in her little pink room and looked at the necklace in her hand. She thought of the kind-faced man and the red-headed lady. She thought of how he had called himself Doctor, and then John and that he knew her name. She closed her little brown eyes and saw his funny green wand and his blue box. She smiled at how he had talked to it and smiled at how he had talked to her, like she was an old friend; the most precious thing in the universe. And she smiled with the boundless, thoughtless love of a seven year old and wondered when she would see him again.

And in her dreams she felt a warm glow and a bright golden light and the words Bad Wolf….Bad Wolf…

And in the morning, she opened her eyes again.

And she forgot.

~fin~