Author's Note: Ta da! Explanation, ho!

"Woah, woah, woah!" said Buffy, waving her arms around. "Just... no. I mean... no! I get that I did a whole magic thing that brought out the true power of the First Slayer, and that's super impressive, but..."

"That's not why they wanted you," the Doctor agreed. "After all, they've been trying to get you since that first time they invaded Sunnydale. And that was long before you defeated Adam." He gave a small laugh. "In truth, Elizabeth, you're far more powerful the way you are, now, than the way you were when you took down Adam two days ago."

"But that doesn't make sense!" Buffy protested. "All I know about is how to stake vampires! And there aren't any vampires in the future. You said it yourself — there is no possible reason the Daleks could want my brain!"

The Doctor sighed. "That was before I knew about IPSA. And, more importantly, before I knew the Daleks knew about it."

"Huh?"

The Doctor turned to Jordan. "How long have you been fighting the Daleks out here?"

"A hundred and fifty years," said Jordan.

The Doctor turned back to Buffy. "One hundred and fifty years. One hundred and fifty years they've been fighting, and the Daleks have gained no ground whatsoever. The Daleks call the Slayers the Vretchip Cruptor. The Impenetrable Barrier."

Laura and Jordan stood up straight and tall at the title, as if it were a badge of honor that each of them wore.

"That's incredible, Elizabeth," the Doctor continued. "That never happens. Even during the Time War, boundaries crumbled, time zones shattered, and the front line constantly shifted. Yet here, facing a group of women who read 'human' on all Dalek scans, the Daleks have been halted."

Buffy glanced over at Jordan and Laura, trying to take this all in. Then she shook her head. "Okay, I think it's time for hyper-explanation mode. What's going on?"

"A hundred and fifty years ago, the Daleks came to the 39th century to attack the Galactic Federation," the Doctor said, "but they encountered a group of humans that didn't exist before the Time War. A group of human women that were strong, well trained, strategic — able to move and think in ways the Daleks didn't expect."

"Like Adam and the Carflodashians!" Buffy said. "Adam has totally screwy data on the Carflodashians, so he always underestimates them."

"At first, that was true," the Doctor agreed. "And the Daleks assumed that was all there was to it. So the Daleks learned. Studied what the Slayer was and what she could do. They thought this would allow them to gain the upper hand. But... well, you can see. A hundred and fifty years later, and nothing. The Daleks still can't get past them."

"We fight for freedom and justice," said Jordan. "We have a strength they can't hope to match."

"They have a role model," the Doctor told Buffy. "Someone they look up to. Someone they all try to emulate. And while they have that role model, that purpose, that inspiration, they will always have hope. They will always have strength. They will always strive to push themselves that much harder, make themselves that much better. Ensure they live up to their legacy."

Buffy met the Doctor's sweet green eyes with her own. Oh, yes. Buffy knew about role models like that. She knew about role models like that all too well.

"Well, I know who my role model is," said Buffy. "Who's theirs?"

The Doctor gave Buffy a pointed look.

Buffy looked down at her borrowed clothes, and sighed. "Oh, don't tell me it's Emily Dickinson!" she said, waving her arms in exasperation. "I mean, I know Owen was all obsessed with her, but—"

"Bunfy Sompters," Laura breathed, in a sort of enraptured awe.

"Buffy Summers," Buffy corrected, automatically, without glancing back at Laura. "No, but, seriously, Doctor, Emily Dickinson's just a poet, she couldn't..." That was when she processed what Laura actually said. She spun around. "Hang on, what?"

"It's you," said Laura. "We all want to be like you."

"Bunfy Sompters," Jordan confirmed. "The most brilliant strategist of her day. The one who battled off impossible odds, and always managed to come out on top. The destroyer of Olvikan, the vanquisher of the Abomination, the defender of Earth. It's said she faced down the essence of pure evil and still managed to emerge the victor."

Wow, these guys had exaggerated her victories! Essence of pure evil? That was a seriously melodramatic way of saying that she staked a few vamps.

Buffy turned back to the Doctor, her eyes demanding an explanation.

"The Daleks wanted your brain," said the Doctor, "because you're you."

"They... they wanted to take her out of history, right?" Jordan asked. "To make sure IPSA got wiped out before it started, and..."

"No, remember the gravestone we dug up in Somelydaya two years ago!" Laura said. "Bunfy Sompters died before the Slayer Institution was ever founded. It wasn't founded by her. It was just founded based on her legacy. Even if you took her out of time, that wouldn't have changed!"

Gravestone? They'd... found her gravestone?

1800 years in the future or not, that was seriously, seriously creepy.

The Doctor placed a hand on her shoulder — a gesture that somehow took away that horrible chill that had come across her from the previous little banter.

"The Dalek Supreme noticed that the Slayers had a power far greater than anything they'd encountered before," said the Doctor, "and decided to get that power working for him. Problem is, Daleks can't hope, or dream, or inspire. In fact, they're certain these traits are weaknesses. So they decided IPSA's power must derive from the Slayer brain. And who was the most brilliant, most strategic, most creative Slayer of all time?" He smiled at Buffy. "You."

Buffy tried to take this all in. Tried to take in how this all worked together, what this all could mean.

"So... let me get this straight," said Buffy. "The Daleks wanted my brain. And the Fountain — to defeat Adam and IPSA and whoever else they felt like disintegrating. But also my brain. So they went back in time, found me, and captured me. And then they just... left me alone for a while, doing nothing. Not harvesting my brain. Just twiddling their..." She glanced down at her thumbs. "...sink-plungers until you could show up and rescue me." She raised her eyebrows. "I think I've found a flaw in your logic, Doctor."

"They were probably planning to bring you back to the 39th century so the Dalek Supreme could cut you up himself," said the Doctor. "They didn't realize I was coming to save you. In fact, until I arrived on that Dalek ship, the Daleks probably had no idea that you and I had any sort of connection."

Buffy said nothing.

"The Daleks must have detected my TARDIS," said the Doctor, "when I rescued Willow. They tried to check in with their Dalek Supreme, figure out what to do about me. But their transmission was scrambled by that TARDIS-repelling spell you shoved in the vortex a short time in the future. After a while of their communications not working, they decided to simply slice open your brain right then and there. That's when I walked in."

"But they didn't exterminate you," Buffy pointed out. "Even when you goaded them."

"Of course not! They were stalling me," the Doctor said. "Trying to get the Fountain, so they'd at least have succeeded in some part of their mission." He gave a shrug. "That particular group of Daleks was incredibly incompetent. Probably didn't even know the real plan. And with good reason. Dalek Supreme wouldn't have sent his best soldiers after you — what with your reputation being what it is. He probably assumed that particular temporal team would be hacked apart."

"Hacked apart, disintegrated," said Buffy, with a shrug. "Same diff."

"Then he'd learn from their mistakes," the Doctor said, "and come back for you later. With an army."

Buffy felt a chill run down her spine.

"Course," said the Doctor, "that particular Dalek temporal team did return to the 39th century, just after they retrieved the Fountain. They told the Dalek Supreme what happened, informed him that you knew me. The Dalek Supreme must have done a bit of sifting around in our past using that Temporal Playback gizmo he showed me, later, and came to the conclusion that I would always rescue you. No matter what. Even if the Daleks exterminated this incarnation, my past incarnation would come in and rescue you, instead."

And if the Daleks exterminated the Doctor before he'd ever met Buffy, then that whole whatever-mistake-thing the Doctor had done during World War II wouldn't have happened, and the Daleks would wipe themselves out.

"The only thing that would stop me from showing up to save you," said the Doctor, "would be if doing so required crossing my own timeline."

"But you have crossed your own timeline," Buffy protested. "Remember? Later-you came around while past-you was stuck in the Initiative."

"Later-me," the Doctor agreed. "But later-me wouldn't be able to drop by if I wound up dead at the end of all this. And younger-me would check the TARDIS and see there was already a Doctor in this time and place, and assume that I was successfully saving you. Which means no doubling back."

Oh. Okay. That made sense.

"So, knowing this, the Dalek Supreme devised a new plan," the Doctor continued.

Buffy was starting to see where the Doctor was going with all this. "Make sure that you were already here, fighting off Adam, while the Daleks were dissecting my brain," said Buffy. "If Adam wanted your TARDIS, you'd send it away. So no super rescues using the TARDIS, like you did last time."

The Doctor nodded. "The calibration test we sabotaged," he said, "was not designed to calibrate the Fountain. Or the Genetic Disintegrator. That test was calibrating me. And it was calibrating you."

"What could make us split up," Buffy said.

"And how we worked together," the Doctor agreed. "What the two of us would do, facing off against the Daleks."

"And Julie?"

"I suspect," said the Doctor, "that they were worried she'd tell you what was going on. Which would be the same reason they'd want the information out of my head, as well. Not because I'd find out. But because you would."

"But why did the Daleks transport me to 39th century Earth?" Buffy asked. "Why didn't they transport me directly onto—?"

That was when a loud bang erupted through the air, and the ship juddered and shook, the four of them struggling to keep their balance.

"You know what? Never mind," said Buffy. "Whatever the Daleks' plans are, they can wait until we're done escaping from them."

"Good idea," said the Doctor, flipping the sonic from hand to hand. "Luckily, I've just formed a plan."