Buffy greeted the Shadowmen, three men in African robes.
 
We cannot give you knowledge. Only power.
 
“Is more power what will beat the First?”
 
We are at the beginning. The source of your strength.
 
Now we are at the end.
 
You are the Hellmouth’s last guardian.
 
“Latest. You mean latest guardian.”
 
The last. This is why we have brought you here.  
 
“I thought I brought me here. Listen, you guys. I'm already the Slayer, bursting with power. Really don't need any more.”
 
The First Slayer did not talk so much.
 
“Tell me something I don’t know.”
 
As you wish.
 
The Shadowman with the red hat touched her temple.  Buffy’s expression changed to one of shock and fear.
 
“How can I fight them? There were so many,” she asked.  “They can never escape the Hellmouth.”
 
We offer you power.
 
It is all we have to give.
 
This will make you ready for the fight.
 
“If I do this, can I win?”
 
The three Shadowmen exchanged a look, then Buffy found herself in a cave, a sacred circle at the center.  The man in the red hat fetched a box and brought it to the center of the circle.
  Herein lies your truest strength.
 
The energy of the demon. Its spirit.
 
It must become one with you.
 
“There’s no other way?”
 
This is all there is.
 
This is what you came for.
 
She sighed in acceptance.  “Fine. Do it, before I change my mind.”
 
The men started rhythmically tapping their staves against the ground.  Black smoke came out of the box in long tentacles; it seemed sentient as it danced around the circle.  The men kept tapping their staves.
 
“This is how you--”
 
Created the Slayer? Yes.
 
The black smoke came toward her, entering her body through her nose and ears.  She screamed.  The smoke recoiled and regrouped, coming in from a different angle.
 
Do not fight this.
 
Accept the heart of your power.
 
Buffy tried to control her fear and closed her eyes as the black smoke neared her again.
 
***
 
The exchange was made.  Buffy came back into the living room, the portal closing behind her.
 
“Buffy!”
 
“Your eyes!”
 
Buffy’s irises were orange instead of hazel, her eyes glowing in the darkness.  The humans were wary, her friends conflicted.  She looked at the vampire, the two halves of her at war over how to react.  He seemed to be struggling in a similar fashion.
 
She needed to get out, outside.  These walls were too confining.  She strode out of the house, ignoring the bombardment of questions.
 
Fresh air.  Better.  The craving to hunt welled up too strong to ignore.
 
The speed.  She was flying; only, her feet still touched the ground.  Almost as fast as she thought of it, she was at the nearest cemetery.
 
As she crushed the first vampire she found, she realized: This wasn’t like the First Slayer.  It was more.  Like—
 
The joining spell when they called up her essence.  Sumerian for the win.  Buffy didn’t have Willow’s magic or Giles’ knowledge, but the power was here, right down to her fingertips and tippy-toes. 
 
She cleared out a vamp nest of a dozen with ease, moving faster than they could see.  And they feared her.  She could practically taste it.  Ripping the head off the last one, she finally felt calm enough to examine how she felt.
 
“Enjoy the show?” she said, her back to the open door.
 
“What I could see of it,” Spike said.
 
“Come to see if I’m evil?”  She turned to face him and sat on a sarcophagus.
 
“Your eyes are the right color again, so that’s a plus.”
 
“Huh?”
 
He relaxed at the classic Buffy response.  “Orange. Glowing. Not exactly human.”
 
“Really? Huh. I’ll have to check a mirror next time.”  She noticed he hadn’t come any closer. 
 
“Care to explain what happened, love?”
 
“There were these guys, the original Watchers I guess, that made the Slayer. They showed me what was in the Hellmouth.”
 
“Not puppies and kittens, I wager.”
 
She shook her head.  “Emphasis on the no. They offered me power for the fight.”
 
“Slayer mojo.”
 
“Yup. How wigged out are they?”
 
He snorted.  “The usual. Red was gonna do a locator spell.”
 
“Are you afraid of me?” she asked, curious.
 
“Should I be?”
 
Typical Spike.  She smiled.  “I hope not. I still don’t know if this will be enough.”
 
“Comin’ back, then?”
 
“Not yet.”  She had the urge to run all night.  “Tell them…I’m okay. I’ll be back by morning.”
 
He nodded, and left her alone.