Title: Encounters in the Fourth Dimension
Rating: PG-13
Characters: Mainly the Doctor, Donna, the Scoobies, but anyone could make an appearance
Disclaimer: I don't own Doctor Who or BtVS. BtVS belongs to Mutant Enemy and Doctor Who to BBC. Written for fun, not profit.
Spoilers: Well, basically everything for both series. Specifically, seasons 2 and 5 for BtVS and the 4th season of NewWho.
Summary: When the Scoobies meet a rather odd pair, they discover that time does not necessarily have to follow a strict progression of cause and effect.

Chapter 1 – First Meetings?

"When I said California, Spaceman, I meant someplace with shops, sea and sunshine! I didn't mean some backwater town with one Starbucks!"

The voices filtering in from the closed library doors made Willow pause just before opening them. Her brows furrowed in confusion at hearing the unfamiliar British female voice. She felt uneasy. Who would be visiting the library this close to the full moon? She could only hope that the woman was some friend of Giles'. But she still didn't want some stranger in the room while Oz transformed.

"Now, Donna, this is just a detour. This place has been going wild with spacio-temporal disturbances recently. Well, I say recently, with time being what it is, this could have been going on forever from your perspective, but-"

This was a man's voice, also British. Willow exchanged a puzzled glance with Oz. He raised his eyebrows and shrugged. His posture seemed to exude only calm, but Willow could feel the faint tension thrumming through him. He probably didn't want strangers in the library either.

"Oi! Don't need a dissertation on the space-time continuum. What I want to know is how soon we can get out. This place was creepy enough the last time and your detours never end well."

Uncertainly, Willow pushed open the doors. They couldn't delay any longer; the sun was going to set any minute.

"That time on Castrogoria 7 was not my fault! It was completely – oh, hello."

The last was said when the stranger had turned around and noticed their entrance. Willow felt nonplussed at the bright grin sent their way. The man was tall and thin, dressed in a brown pinstriped suit with a long tan overcoat on despite the stuffy heat of the library. The woman with him was dressed more appropriately for the weather, but she seemed just as out of place as he. Her hair was red like Willow's and her stance was more confrontational than his was. She looked annoyed, but her annoyance was obviously directed at the still grinning man.

"H-hello," Willow said uncertainly, glancing at Oz again. He squeezed her hand in support before moving towards the cage, his eyes never leaving the two strangers. Giles was nowhere to be seen and Willow felt a faint jolt of panic run through her.

"Brilliant to see you again!" The man strode towards her, putting something away in his pocket. He grabbed hold of her hand and shook it, his grin wide and eyes gleaming.

"I'm the Doctor, that's Donna, say hi Donna!"

Donna waved from behind, smiling sympathetically at Willow's confused expression.

"Aga- wha? Can I help you?" Willow managed to get out, looking to Oz in a rising panic. Sunset was quickly approaching. The Doctor followed her gaze and his grin widened even further.

"Oh, don't mind us, we're just-"

"Just in the neighbourhood," Donna cut in, glaring at the Doctor, but smiling at Willow, "We'll be out of your hair soon." She said pointedly to the Doctor.

"Right, soon, quick, in a jiffy, you'll hardly ever know we were here," the Doctor agreed, finally releasing Willow's hand. He moved away and took out a silver pen like object, waving it slowly around. Willow noticed he was slowly, but surely circling around the center table and beginning to frown.

Oz and Willow looked at each other again. 'What do I do?' Willow mouthed to him. He frowned, glancing at the clock.

"No time," he said grimly and stepped into the cage, shutting it firmly. Willow spared another worried look at the two strangers before she approached the cage.

"I'll be right here when you wake up," she promised, "I'll keep you safe a-and get them out somehow."

Oz quirked his lips into his version of a smile.

"Never doubted it."

He grimaced, "Don't watch."

Willow only nodded, worrying at her lip.

"What do you mean it's not working?!"

Willow winced as Donna's loud voice suddenly reminded of their unexpected visitors.

"Too much interference," the Doctor started saying, running a hand through his hair and making it stick up in every direction. He grimaced slightly, rubbing at his temples.

"This place is a mess. It's like a hodgepodge collection of bits of space and time strung together and held in place by a piece of string. And not nice, smooth string, more like twine with pieces sticking out and poking and dragging across your skin unpleasantly. Sort of like nails on a chalkboard."

"Yeah, alright, so it's unpleasant. Get to the point, Spaceman!"

"Donna, really-"

Willow breathed in deeply, ignoring their bickering for the moment (although she would really have to find out what the heck they were talking about). She had to get them out before Oz started transforming. And if it meant shouting…well, she'd done it before and for Oz she would do it again.

"The readings are bouncing around like a rubber ball. I had one of those once, although it wasn't made of rubber so much and when I say ball, well, it was more of an oblong shape-" the Doctor had turned around towards the cage during his rambling explanation and suddenly stopped. He paused and looked up straight towards Oz's cage, eyes wide with surprise.

This was bad. Very bad. She had ran out of time. The sun had set and Oz was already doubled over in pain from the beginnings of the transformation.

"I-I'm gonna have to ask you to leave!" She started babbling at them, eyes wide, trying to move Donna towards the exit ("Oi! Watch it, miss Motormouth!"), "We're busy here with the reshelving and cataloguing and it's a very delicate process that's really very private because Giles is British and he has these weird notions about it, not that you're weird for being British obviously-"

The Doctor was ignoring both her desperate rambling and Donna's snickered accusations that he had found someone to rival him in the gob department. Instead, he was pointing the strange gadget at Oz. Willow stiffened and raced to the cage where Oz was growling and snarling, still in the middle of transforming, but all it did was produce a soft whirring noise with the blue light at the end of it turning on. The Doctor looked up at Oz and then back at the small device. He did it a few more times before breaking out into a wide grin.

"Oh, this is brilliant!"

"What's the matter with him then?"

While Donna sounded concerned, the Doctor looked entirely too gleeful and Willow's mind flashed back to Cain and stories of other werewolf hunters. She glanced around before spotting one of the wooden staffs Buffy and Giles had practiced with this afternoon propped up against the cage beside her. Suddenly very grateful for Buffy's tendency to forget to clean up after training, she grabbed it and brandished it in the direction of the Doctor and Donna. Behind her, she could hear the shifting and cracking of Oz's bones and felt vaguely sick.

"Yeah, well, you can just forget about…about any evil plans you have for him, mister! I'm not letting you hurt him! GILES!" she yelled for the absentee librarian. Normally, you couldn't even separate him from his books, but now that she needed backup, he was nowhere to be found. Behind the Doctor, Donna winced. A distant thud could be heard amongst the stacks of the library.

"Hurt him?" the Doctor looked confused, before his expression cleared, "Oh, no. No no no no no no no! I wouldn't hurt him! This is just brilliant! Absolutely brilliant!" He bounced on the balls of his feet, "I haven't seen a proper werewolf in ages!" As though to punctuate the words, Oz crashed against the cage door, snarling. "Of course, there was that time in Scotland, but that was completely different! Well, I say different, I mean-"

"Doctor!" Donna interrupted him. She looked annoyed more than anything else. She was glaring at the Doctor, hands on her hips.

"Hmm?" he turned towards her, still beaming.

"Crazy girl with a stick threatening to crack your stupid head open?"

"What? Oh!" he grinned at Willow, "She's not going to crack my head open."

"O-oh yeah? Just watch me! You're not getting Oz! I'm not letting you hurt him o-or kill him or try to take his pelt or run experiments on him, so you'll just have to get through to me first, mister!"

"Looks pretty determined to me, Spaceman," Donna said wryly. Although she seemed remarkably unconcerned about Willow waving the staff around, despite her warnings. Willow didn't know if she should feel offended or not. Surely she was at least a little bit threatening?

"B-but, no seriously. She literally couldn't crack my head open with it," he seemed confused that Donna would contradict him at something that was so obvious to him, "She couldn't get the needed velocity or force with the grip that she has and the angle is all wrong-"

"H-HEY!" Willow shouted to gain their attention,"I'm the one with the stick, so I'll be saying who gets to crack what around here!" she glanced from Donna to the Doctor in angry confusion, "Now, explain who you are and what you want and if this wasn't clear enough - NO MESSING WITH MY BOYFRIEND!"

The cage rattled behind her as Oz in wolf form slammed into it again, growling. Willow jumped, her grip on the training staff loosening.

"Aw, that's brilliant! Did you see that, Donna? That's what I love about you humans. Most people would just run away if they found out that he was a werewolf, but not Willow! She goes and gets involved with him. You lot always keep surprising me! It'll be a few more centuries yet before most of you get rid of all of the hang-ups you have."

He had moved forwards as he talked and ended up right next to the cage. He stared at Oz. Oz stared back at him, growling softly. Willow gaped at him for a moment. How had he known her name? This situation had not only become freaky and not in a good way, but had already passed that point and entered into the realm of downright weird.

"Oh, you are beautiful!" the Doctor beamed at Oz. Oz rattled the cage, fangs flashing as he snarled. The Doctor didn't even flinch, but kept staring, his expression completely awed and excited. He didn't seem like much of a threat, to be honest, but this was the Hellmouth and you could never be too sure.

Which is why Willow grabbed at the fallen staff, ignoring Donna's muttered 'mad bloody Martian' and was just about to smack the guy over the head when she froze at Giles' startled

"Good Lord!"

Before Willow could do more than flinch away, the Doctor had bounced around to face the flabbergasted Watcher. He grinned delightedly.

"Rupert! Lovely to see you!" he bounded up the stairs to the raised landing where Giles had appeared, book in hand. The Doctor grabbed Giles' hand and shook it enthusiastically. Willow's hand throbbed in remembered sympathy from suffering the same greeting.

"Love what you've done with the place, although I have to say I prefer the shop. It's a marvellous shop. Have I mentioned that I love little shops? It doesn't have to be big, just a little shop and yours was - well, will be brilliant!"

"Giles?" Willow asked weakly, feeling more than a little overwhelmed "Do you know him?"

"I have never met him before in my life, Willow," Giles looked a little dazed at the babble spewing forth from the Doctor.

"And have you met Donna yet?" he vaguely waved a hand in Donna's direction where she had taken a seat at the table, her posture impatient and resigned, "You'll love Donna, she's brilliant and what do you mean you've never met me before?" The Doctor finished with a confused expression. Then he brightened.

"Oh right! Crossing my own timeline again. I don't suppose you'd remember seeing how it hasn't happened for you yet. Blimey, this gets confusing! And the first time we met-"

"I do beg your pardon," Giles finally reclaimed his hand, stiffly adjusting his glasses. He had obviously caught his second wind and was now starting to rally against the intruders in the library. Willow only felt slightly reassured by the cold gaze he aimed at the Doctor; Giles could be damn scary sometimes, even when the threats weren't ever aimed at her, "But I am quite sure that I have never met you before in my life."

"No?" the Doctor seemed to wilt slightly. "Well, can't be helped I suppose. You were ten at the time. Or was that eight?" He grinned brightly at Giles again, as though he would helpfully correct him.

"I think it best if you started explaining yourselves, now." Giles' tone brooked no arguments. The Doctor sighed.

"And this, Donna," he said to her, "is why crossing your own timeline is generally considered to be a bad idea, not to mention rather awkward at social gatherings. Well, that's if you discount the possibility of causing a paradox big enough to destroy two thirds of the universe." The manic grin was back on his face.

At this, everyone stared at the Doctor, who didn't seem all that disturbed by the thought. The library doors opening were the only sound in the sudden silence that had descended on the library.

"Giles?" Buffy called as she entered, "Why is there a blue Police Box thingy in the hallway?"

TBC