Supernatural is owned by Eric Kripke and Buffy is owned by Joss Whedon.
She was by far the most beautiful thing they had ever summoned, that was for damn sure, and Ripper was almost sure she was the most dangerous. He wasn’t foolish enough to believe that the pretty face she wore was even her face, let alone the body it was attached to, but he could still appreciate the loveliness of what she had stolen. She had copper curls chopped off just below her jaw and fine features, which wore a dangerous little smirk as she looked at him and his friends from within the Devil’s Trap they had confined her to.
“Silly little children,” she purred, her borrowed voice lilting with an Irish accent. “Didn’t your mothers ever tell you that if you play with fire, you get burned?” Her eyes faded to pitch black and he’d be a liar if he said he wasn’t unsettled.
Ethan, full of bluster and arrogance, strolled right up to the edge of the circle painted on the floor. “Demon,” he began, “or is it Ruby? I’d heard that’s a name you prefer.” At her nod, he continued, “Well, then, Ruby, the situation is simple. If you do what we want, you go free, and then everyone is happy. Does that work for you, love?”
Ripper watched the demon tune out before Ethan had even finished his first sentence. Her eyes travelled lazily, almost hungrily over the group gathered before coming to rest on him. He felt his blood run cold as the black slipped out of her eyes and she tilted her head to the side in interest. Her eyebrow jacked up as she studied him and she said lightly, as if she was talking about the weather, “You don’t belong with this crowd, do you, darling? You smell like a Watcher and your soul burns with goodness.”
She blinked once, considering, before turning back to Ethan as if she hadn’t just spoken. “I doubt everyone will be happy by the time this is over,” she told Ripper’s best friend, shrugging daintily. “But who knows? I’ve been wrong before. So tell me just what it is you want.”
She and Ethan discussed terms and conditions for awhile before everyone seemed satisfied and she smiled like a cat about to get the drop on a certain yellow bird. Not for the first time, Ripper got the feeling something terrible was going to happen.
Ruby said to Ethan, “Come on, then, and plant one on me, fella. Seal the deal.” She puckered up ludicrously, like a child. Ethan frowned a little, but complied, stepping forward and leaning into the circle to meet the demon’s lips. There was a split second as Ethan’s torso entered the Devil’s Trap where Giles knew they really had played with fire and this was when it would burn them. Ruby’s hand shot up faster than should have been possible and fisted in Ethan’s shirt, dragging him against her. She made sure to drag him, made sure his feet scraped across the lines painted on the floor and damaged them.
The demon stepped out of the prison they had made for her, Ethan’s back pressed to her front as she used him as a shield. She smirked triumphantly. “What did I tell you? You play with fire…” Then she was a blur of motion and destruction.
Sometime later, Ripper found himself on the floor, drifting in and out of consciousness. His eyes fluttered open and blearily tried to take in the bodies crumpled on the floor around him and the blood splashed on the walls. It was a moment before he registered that Ruby was crouched at his side, watching him intently. He flinched as she leaned towards him, but all she did was press her lips to his, giving him the kiss she had tempted Ethan with. She looked at him like he puzzled her before she said quietly, solemnly, “I have a feeling we’ll meet again.” Then she – the flame - was on her feet and gone, leaving behind only scorches.