The characters of the Alien and the Predator are property of 20th century Fox. All characters from the Buffyverse are Property of Joss Whedon. Everything else belongs to me.
Buffy walked through the front door of her home. She stood there for a moment watching the world around her with eyes as wide and unblinking as the eyes of a newborn child. Everything here was new to her and at the same time old and wrong. She was no longer just Buffy. She held within her billions of years of alien memories that informed her of the true nature of the universe and at the same time the full power of the slayer flowed through her demanding that she slay. Buffy no longer considered herself Buffy. She knew herself as Hive. It was the name of the world she was going to build. It was the name of the mind she wore in the veil of her flesh.
A gaggle of girls came to her. They were the potentials, girls marked by the same spirit that possessed her now. Buffy let her gaze slide over them. She realized just how weak and irrelevant they were. Alien memories had already informed her of the presence of the Turok Han under Sunnydale high and how to defeat them. As Hive, she considered the potentials a joke.
Dawn burst through them.
“Buffy!” She exclaimed. Dawn was a fifteen year old girl with brown hair and brown eyes and the beginnings of hips. Dawn moved towards Buffy who stepped back sharply. The key was here! The twin helix of the key illuminated the room with its green dimensional energy. Along the edges of Dawn Buffy could see space and time ripple as her energies ate away at the integrity of the universe. The key was death which made Dawn a monster and she was the slayer of monsters.
“Don’t do this.” The memories of Willow said to her. “She’s your sister!”
Buffy responded to the Willow within. “The Key is the enemy of the hive.”
Giles walked through the door. At a glance he could tell that there was a tension between Buffy and the other girls. He expected something like that. Earlier tonight Buffy had defeated an alien Predator in hand to hand combat by invoking the joining spell. The full power of the slayer flowed through her now. But in addition, she also had the blood memories of the entire xenomorph species. A billion plus years of memories burned in her mind. Buffy knew unspeakable secrets. She was the memory of the living galaxy made flesh. It took Giles only a moment to understand the reason for the tension. Even as he moved to interrupt the creature that Buffy had become, he knew it was too late.Across the galaxy near the Yautja home world:
Four kings sat around a fire. In the center of them advance holographic technology replayed events from far across the galaxy. A Yaujta fleet had recorded the end of the long hunt
and the death of Barik Null. These kings knew Barik. He was the stuff of history and legend. More than one religion had sprung up around the tale of how Barik was taken by monsters and forced to hunt in the afterlife, tales of how he was enslaved by devils and forced to become the slayer of slayers. They knew Barik in other ways too. The long hunt had started over ten thousand years ago. Every king here was one of his descendants. They watched the pale holographic image of Buffy Summers floating in the air. They watched as fire sprung from her hand. They watched their ancestor die with honor .
The image faded. They talked among themselves for hours. When it was done they were all agreed. Barik died with honor but he was not used in an honorable way. The Senior Partners had used him to kill girls young enough to be considered children. The decision was unanimous. They were owed a debt of blood. They would hunt the Senior partners and collect the blood debt.
But that was not the reason they were here.
Each of the four kings stood before a remote access panel which was a round dais with oversized palm sized scanners. They stood together in a circle with the palm of their right hand pressed into the cold glass screen. The device they summoned could only be activated by their living DNA. On the device, lights flashed from red to green. The command was given. Light years away machines flashed to life. Planet sized masses began to move towards the black pit. The Yaujta had activated a particle beam weapon powered by a black hole the size of a solar system. If necessary, they could throw stars into it. When they found the Senior Partners they would kill them no matter where they hid.
The kings departed. Each of them went to their respective flagship. Above them, over a million Yaujta battleships waited for commands. The children of Barik Null would have their revenge.
Buffy approached Dawn. The thing that pretended to be her sister had to know. "The vessel has outlived its purpose." Buffy said to her. “You must be removed.”
“What?” Dawn said. A slow realization came to her. This was not the first time she had seen Buffy go crazy and try to kill her friends. Dawn pleaded with her.
"Please Buffy, I am your sister." Buffy looked at her. Her eyes were bright, vacant and cold. "You are the vessel." Buffy said. "You shouldn’t be here."
Buffy waived her hand and spoke a spell only she knew. As she was crying, as she was pleading for her life Dawn faded into nothing along with all the memories attached to her. Afterwards, only Buffy ever knew she ever existed. The others looked around the room then at each other as if awaking from a dream.
“I have to fix this world.” Buffy said. “It is broken and I am the law.”