A miscast spell from a erotic spell book leave Cadance under the power of a demon parasite that just won't leave her alone.

Are they going to bond, and have babies? It would be interesting if Flurry Heart turned out to be a demon pony hybrid due to this.

9960180
That would be interesting, would be more interesting if cadence somehow tricks it into taking the form of flurry heart

I just can't wait when you put horror in there.

This is so insidious there's nothing cadence can really do but just exist and accept whatever the parasite wants her to do

About the only good she could say about it was that it didn’t tease her constantly. It just worked her up to the level of having difficulty thinking of anything but sex and then stopped, only doing small touches to keep her there.

Good enough, though.

She still shuddered at the sight but then lit her horn and went on with brushing her mane, “You don’t need to tease me all the time,” she told it.

Well...

9963573
At least for now. She might stumble upon a solution later.
Either to ged rid of it or to make sure it "plays nice".