DISCLAIMER: I own nothing, as you well know.
"You're sad." River observed, staring at Oz.
"Maybe a little." She continued to stare at him until understanding crossed her face.
"Your fire is dancing with the earth, and you can't get it back." He looked up, understanding what she meant.
"She's happy. I couldn't stay there, making her miserable every time she saw me; I couldn't hurt her anymore." He spoke softly. River crouched sown beside him and put her arm around his shoulders. Ever since he fell here, this strange man from the past, she'd felt a connection to him, like a puppet to its strings. He understood her. He knew others like her.
He looked up at her wanting to change the subject. He asked her,
"So River, what do you want to hear about today?" every day he'd been telling her stories of his life before coming here; there were many, the next more unbelievable the one before. She smiled. She wanted to hear about the others.
"The ballerinas dancing in the desert of ash." Oz thought a moment before it clicked: Slayers.
Talking with River was like solving a giant riddle. He enjoyed it, it was challenging; no-one else ever took the time to really listen to what she was saying, not even her brother. Hidden underneath the cryptic wording was things he didn't understand how she know. She was wiser that anyone else on this ship; they just didn't know it.
"Slayers." He looked at her carefully, hoping to confirm what he already believed. "Like you?" She nodded, the smile still there. Oz couldn't smile back. He had hoped that he was wrong, but she just confirmed his worst fear.
What happened to a Slayer when there were no demons to slay? All that strength and aggression couldn't just stay bottled in. Slayers had to fight, had to kill' it's what they were made for. He dreaded the day she couldn't hold it in anymore, when the violence took over.
Coming back, he saw those curious eyes looking at him expectantly. She had the most beautiful eyes he's ever seen. Clearing his throat, he started his story.
"Well, I knew three Slayers back on Earth, but Buffy was the one I was closest to. She…" Oz continued to tell the tale of Buffy the Vampire Slayer, holding River's attention captive with the adventures of her predecessor. Someday, the insanity on top of the Slayer powers might become too much, she would be a monster. But this day, she was just a girl.