Rose Tyler had been having the same nightmare every night for a week. She never remembered what it was about upon waking, but she sensed a certain sameness about it and more than a measure of dread.
On the eighth night, as she woke up gasping and panting, she decided enough was enough. She slipped on a dressing gown over her pajamas and decided to go find the Doctor. Not surprisingly, Rose found him fiddling with the TARDIS console instead of his bedroom. Completely oblivious to everything except for the dials and switches that controlled his space/time machine, he didn't even notice Rose's presence until she spoke.
"I'm not interrupting you and the missus am I?" she said with a grin. He jumped, startled.
"About time you got up. What time is it, three in the afternoon?"
"Actually, it's five oh six, in the morning."
"Well, what are you doing up then!"
"I've been having the same nightmare for the past week and for the life of me, I can't remember what it's about, only that whatever it is happening in them, scares the hell out of me." Rose sighed, rubbing at the circles beneath her eyes.
The Doctor was half-tempted to laugh or make a sarcastic remark, but he saw the fatigue in her eyes. Not only was she plagued by nightmares, but she probably couldn't force herself back to sleep afterwards either.
"Well, I do have an idea, but it's sort of invasive and I can't promise anything will come of it. It's like a, um, mind-meld."
"How very Spock of you, Doctor."
He rolled his eyes. It seemed Rose always measured his actions in comparison to the fictional Star Trek character. It used to annoy him, but he now found it oddly comforting and familiar.
The Doctor brushed back her long blond hair from her temples and placed his hands on either said of her forehead.

Everything was black around her as she ran towards him, running as though her life would cease if she ever stopped. Yet the faster Rose ran, the farther the Doctor and the TARDIS went away from her. "Come on, Rose, you can do it!" his voice said, getting ever farther and farther away.
Suddenly an idea occurred to her, and she ran in the opposite direction. Her gambit paid off and the Doctor and the little blue box began to approach her.
"How did you know it would work?" he asked.
"Just lucky, I guess." she grinned.
Then everything went gray and the TARDIS vanished and the Doctor stood in front of her, but he wasn't Rose's Doctor, not really. His face was contorted in a hideous leer, his bright blue eyes had turned solid gold, and he seemed to get taller and more frightening by the moment. When he opened his mouth to speak, his teeth were all fangs and his eyes glittered malevolently.
"Are you afraid of the big Bad Wolf, Rose Tyler? No? Well, you should be!" The Not Doctor made to lunge for her and just as he did, the dreamed ended.

The Doctor leapt backward in shock.
"Bad Wolf, everywhere we've gone, it's followed us. What the hell does it mean though? Is it a threat, a warning, a creature, an event? And what does it want with you, Rose?" he thought aloud.
"Want with me? But, it was just a nightmare, Doctor. " Rose shook her head.
"No, it wasn't just any dream. It was like a beacon, a calling card, trying to get your attention. Or mine. Something's been watching us, following our progress this whole time and I've been too blind to see it. And the worst part is, I don't know how to stop it."
"Like fate?"
"I don't believe in fate, not really."
"But you do believe in fixed points. Sounds a lot like fate to me. What if whatever this Bad Wolf thing is can't be stopped? It's followed us across time and space after all. What if it's a fixed point?" she reasoned.
"There are some things I can't change or protect you from, Rose Tyler, let's hope this isn't one of those. Bad Wolf, whatever it is, is a powerful force to be reckoned with. In the mean time though, I think maybe it's best you stay on the TARDIS." The Doctor said gravely.
"What, no! I'm not staying inside this mad box while you go out and about having adventures."
"The only alternative is that I keep watch over while you sleep and- well, that sounded quite creepy out loud."
"Like a sleep-over?" Rose said, bemused.
"Oh yes, we'll give each other make-overs, talk about boy problems, play Tiddleywinks, and have tea. It'll be fantastic!"
"Sounds great, yeah." she grinned.
"It was a joke, honestly, can't humans tell the difference between sarcasm and an actual offer!"
"If it's between that and staying in the TARDIS at every stop, I'll take it."
The Doctor sighed, crossing his arms in front of his chest. "Fine, but don't expect me to let you do my make-up or put my hair in curlers."
"Well, you don't exactly have enough of it, do you?" the girl laughed.