The succubus laughs, stepping over to Japhiel and sliding a hand down his pants. He stops with a gasp, completely shocked as he suddenly must deal with a mortal human's instincts for the first time.
"It's a more than generous offer. After all, I could change you even without your permission... but where would be the fun in that?"
You ponder the offer. You hardly want to go around sucking out people's souls, or turning women into men, and you certainly don't want to spend a day in hell! Still, if she made you into a demon, it would give you the same powers she has wouldn't it? You could simply turn yourself back as soon as she was gone, couldn't you? Even if not, all you'd have to do is lay low for a day somewhere, right?
"Deal," you say. "I'll spend a day seeing what it's like having powers like yours, and this time tomorrow you come take this whole curse off me and we never speak again."
"Excellent," she says with a sinister smile, unhanding the angel and struts over to draw you into a long kiss. Japhiel shouts "No, you fool!" as he recovers his composure, but it's too late. The demonic woman syphons away the angelic influence on your body, shuddering and twitching as a the conflicting enegies mingle with her own, causing her to sprout a layer of bright orange fur and grow an extra seven eyes as she withdraws.
You feel... different as she pulls away. Dirty, but in a good way. Sexy and confident, less concerned about, well, much of anything. The snout growing out of your face quickly snakes its way back to something fitting for a normal human, but as soon as it does, you double over in pain, a forked tail sprouting from the tip of your spine, tiny horns bursting out of your temples, and a sickeningly queezy sensation as your belly flattens and hips flair out. Bringing your suddenly more slender arms to your itchy chest, you feel an incredibly sensitive pair of breasts as they grow and tingle.
"Hey!" you shout, the sound coming out as more of a sexy come-hither tone than the anger you'd intended. "This wasn't part of the deal! I didn't say I wanted to be a girl!"
The succubus laughs again, sprouting a pair of floppy rabbit ears. "Well if you wanted to be an incubus, you shouldn't have asked for powers 'like mine!' I can't affect women after all... and neither can you, if you'd thought to just change yourself back. Trust me when I say you are very much a woman now."
Your attempt to shout back turns to a sensual moan as your body finishes shifting to that of a very, very female demon, still standing around stark naked, with an incredulous Japhiel watching in horror. Looking at him, you can't help but lick your lips at the sight of the bulge in his pants from the succubus... the other succubus' earlier teasing, and you're quite sure you've never been this horny in your life.