Seriously increase the sex drives of the two sisters and see what happens (Fantasy Creatures)
From Create Your Own Story
With a double-flick of your two wrists, you cast one of the Forbidden Spells you happen to know on the two girls. There are reasons such spells are shunned back home. You never really cared what others thought of you, though.
The spell starts affecting the younger sister first. Her eyes dart between the boys across the way and her own sister. She starts jittering strangely. A tension starts building in her face. She bites her lip, staring her sister intensely in the face.
"You okay, Lyra?" her older sister asks.
At that moment, the spell kicks in for her as well. Her pupils dilate, and her right hand reflexively grabs between her legs.
"You feel that, too, Josie?" the younger one asks.
Some sort of unspoken signals are exchanged between the two through just their eyes alone. Before you can even realise just what you've done, the girls are all over each other. Lyra moves first. She pushes against her sister, and begins kissing her neck. Her hand goes between her sister's legs as though it had been magnetised. Her sister gives her the exact same treatment. The two sisters are now vigorously rubbing each other between the legs through their clothes, and their lips are all over each other. You can hardly believe your eyes. For the spell to have worked like this, the girls must've already been attracted to each other and were just hiding it all this time.
You look over to the boys, realising they must be privy to the exact same spectacle as you. Their eyes are wide, and their jaws have dropped. Honestly, they're almost exactly mimicking your own expression. All they need is a pair of wings.
Looking back at the sisters, you see things have taken an even stranger turn. Josie's clothes are being torn from her body by her rabid sister, while Lyra tries to take off her own clothes at the same time. All semblance of shame has been lost. Lyra knocks her sister to the floor, and quickly removes all clothing off of the both of them. Utterly naked, she grabs her sisters leg, and pushes her crotch against hers. She starts gyrating her hips, and the two begin softly moaning.
Watching this thing is starting to get you a little worked up yourself. You might want to alleviate that tension you've got.
Do you…
