Ringworld is property of Larry Niven. All characters from the Buffyverse are Property of Joss Whedon. Everything else belongs to me.

She could see the arch of the Ringworld from where she stood. The copy of Buffy Summers entered a clearing at the edge of the woods. She looked skyward a moment taking in the checker board pattern of the Ringworld that lay millions of miles away. It was night where she was standing. The shadow squares cast patterns of light and dark over lands distant and greater than all of the kingdoms of Earth.

She was at the shore of the great ocean. Before her, lay tens of millions of miles of water. The ringworld engineers had sculpted the ringworld floor to hold the great ocean and at the same time had sculpted the topology of the basin to mirror all the worlds in known space. The scale of it was awesome. In the great ocean were islands the size of planets. She could see at the very edge of her vision ships that were larger than the empire state building on Earth. She knew, as a fact, that there were ships, actually floating cities, currently in the great ocean where millions of people lived their whole lives.

Both Dawns joined her by the edge of the sea.

Days ago she retrieved the second Dawn. This was the Dawn that had been copied with her to the Ringworld so many years ago. If the Buffy Protector had not screwed up the transfer of her and Dawn from Sunnydale to the Ringworld she would not be here. She world have made all of the same choices that would lead to the creation of the Buffy Protector and the timeline would have not been fractured, but it was. The Buffy Copy that stood at the edge of the great ocean was an unforeseen thing, an unintended consequence of someone else's actions.

"First the dark men call me to be a slayer, then the monks call me to be a sister, then the Ringworld calls me to be a protector. When will my life be my own?" The Buffy Copy thought. She stood silently with her arms crossed starring into the gray mists of the great ocean.

"I'm pretty." Dawn said to herself as she looked her quantum copy up and down. The Dawn from the Buffy Protector smiled at the Dawn that had been transferred with the Buffy copy.

"Why are you still here?" The Dawn Copy asked the Buffy Protector Dawn.

"Magic." She answered. "I was created by a realty augmentation spell. When the timeline was changed, the spell didn't notice. It went blindly along its way anchoring this construct to this reality. The realty augmentation spell is pretty stupid. The Buffy Protector began to suspect this when I was reconstituted after being pulled into a black hole while using my keyness to search the past for the original Buffy."

The Buffy copy could hear their conversation. She briefly looked over her shoulder at them and growled.

"She's cute when she's homicidal." The Dawn copy said and then thought for a moment. "Hey, I'm my own homing beacon!" She said, just getting the implications of what the Buffy Protector Dawn had said.

"And that's not the weird part." The Buffy Protector Dawn said. The Dawn copy looked at her puzzled. "What would you get if you blew up the universe?" The Buffy Protector Dawn asked the Dawn Copy.

"What?" she replied.

"You and I floating through the infinite void forever." The Buffy Protector Dawn said. "As near as the Buffy Protector and I could figure the monks never installed an off switch. There is the possibility that we could live forever. An immortal with the ability to reproduce is not a good thing. Buffy and I did the math one night. I could replace the entire thirty trillion person population of the ringworld all by myself in about four hundred generations. Of course, poor Acke would be all worn out by then, but you get the picture."

"Got any baby pictures?" The Dawn copy asked.

"Sure do." The Buffy Protector Dawn answered as she pulled an image viewer from her stash.

"Will you two old ladies keep it down?" The Buffy copy asked.

"Are we making it hard for you to concentrate on your evil plan to destroy the world?" The Dawn copy asked with as much sarcasm as she could muster.

"So that's your big plan? You're going to get magic to bite itself in the ass, to shoot itself in the foot? Help me." The Buffy Protector Dawn said. "I'm running out of metaphors."

"I'm going to get magic to cancel itself out" The Buffy copy said. "I'm going to make the two sets of augmentation spells notice each other. I'm going to make them fight for supremacy draining all the magic in the process. If I do this right, there'll be no more vampires, no more slayers, no more hell gods, and no more magic." The Buffy Copy looked at Dawn. "And no more you."

"What gives you the right to change the world?" The Dawn copy asked her sister.

"Such decisions have always been mine. I do what's necessary." The Buffy copy said. "I am the dark command."

The Buffy copy removed the branches that covered the general products hull and entered the hidden ship. It was a small suborbital craft just big enough for three people. The Buffy copy fired up the engines as she readied for the twenty hour trip to the Map-Of-Mars. Her ship could do a fair fraction of the speed of light.

"Let's go, everybody in." The Buffy Copy said.

"Should we tell her?" The Dawn Copy thought to herself.

"Not yet, it will be fun to see how far she goes with this." The Buffy Protector Dawn thought to herself. "Let's see if she's smart enough to figure out that she has it all wrong.

The two Dawns continued to talk among themselves telepathically as they silently entered the ship.

Algebraic topology

Think of Dawn as a 5 dimensional octopus sending 3 dimensional tendrils into this universe.