Ringworld is property of Larry Niven. All characters from the Buffyverse are Property of Joss Whedon. Everything else belongs to me.
"Go over it again Willow." Giles asked. He was still in the magic shop franticly trying to reach Buffy on her cell phone. So far there was no answer. "Tell me what's happened."
Willow blew air through her lips while she organized her thoughts.
"First the monks create Dawn from Buffy using her blood. To make Dawn fit they changed reality to give Dawn a background cover. They even went so far as to change memories so that we wouldn't question Dawns existence." Willow said giving a general outline. "And to make sure Buffy would protect her, the monks gave Buffy a mystical compulsion to protect Dawn."
"I understand so far." Giles said as he dialed Buffy's cell phone number again.
"This is where things start to go wrong. The monks bonded Buffy to the biology of the construct. Buffy is bonded to the blood not the person. They were rushed. They never had time to review "Elements of Logic" or such. It never occurred to the monks that Dawn would live long enough to reproduce.
"So let's say we get out of this, we live and Glory is gone. Apparently the monks never came back and uncreated Dawn, never put reality back the way it was. Dawn grows up, has kids, those kids have kids and those kids have kids until at some point in the future billions of them are occupying the ringworld. Normally it wouldn't matter. The protector spell on Buffy would have never been affected by those descendants if the wormhole had not created a short cut in both space and time alerting the protector spell that billions of little Dawns exist out there. The sad fact is that most monks never really study advanced physics. Sure, they sign up for the classes but most of them drop out during the first few weeks."
Willow was trying to be funny.
Giles pocked his cell phone. Buffy had not answered.
"I'm sure Xander will catch up with her soon." Giles said. "Does Xander have a cell phone?"
"Yes." Willow said as she held it up for him to see. Giles rolled his eyes. Willow continued.
The problem is not that Dawn exists. The problem is that Dawn persists. She affects the universe in ways the monks never considered. As far as the ringworld goes, here's an allegory. The ringworld is to Buffy as a full moon is to a werewolf. As long as the mystical compulsion in Buffy is aware of Dawn's descendants through the wormhole she will feel the pull to protect them. As soon as the wormhole drifts out of position things will return to normal. Buffy can go back to obsessing only about Dawn."
Willow thought about the cute purple umbrella they had given to Buffy with the plaque that read "Class Protector." Buffy was way past that now.
"Any idea of when the wormhole will drift out of position cutting the protector spell's connection to the ringworld?" Giles asked.
"Not a clue.' Willow said. "The wormhole is relatively close to the ringworld and the ringworld is hundreds of light years away. That's one stable wormhole. I need to research more to determine how long it will take the solar system to drift out of the cone of its influence."
"In any case, Buffy's not leaving the Earth. What is she going to do? Hijack a spaceship?" Giles said.
"Or build one." Willow mumbled.
"What?" Giles couldn't believe what he had just heard.
"Didn't I tell you? Buffy's a genius now."