The prison had been built some time ago, specifically to house the most dangerous creatures of the world. Those born with supernatural abilities, or those who had inherited them in some way, shape, or form. If not for the one simple thing that had happened between them, he would have never been there. However, she'd said it would be glorious. And the pale demoness had been right. It was glorious. In the moments up until everything had happened, it had been the greatest night of his life. Unfortunately, that much power being summoned had also attracted the attentions of the, for lack of better terms, good guys. While he should have known who she was, it didn't matter. Guilt by association, and here he was. Imprisoned.
Having sex under a crucified body, a man if he recalled correctly, blood pouring down upon them throughout the sexual acts, had been something he'd never dreamed of. Smiling fondly at the memory, he leaned back in his cell, head against the wall, staring up at the ceiling. He had been a mundane before that had happened, granted, a twisted mundane, but he'd had no powers before she had done the conjuring. The power needed to break through the barriers between this world and the next, to crack the walls of Hell itself, was raised through the acts of sacrifice and sex. He was in the throes of an orgasm when the dagger struck down into his chest, piercing his heart.
The crack had been enough to let forth one of the Fallen, a monstrous creature that had not been heard of since the War in Heaven. Gadriel had taught men how to wage warfare, and his release into the prisoner had been potent enough to warrant immediate imprisonment. The battle had been fierce, but he'd been defeated by the sheer numbers the other side had been willing to sacrifice. A sigh escaped his lips as he ran a hand through his buzzed black hair, perusing the walls around him. This...would be something to deal with until the release came.
Edit: That just kinda tapered off not exactly where I wanted it to go. But yea, prison for the supernatural, mix of creatures all imaginable, that's the picture.