An Imp

You choose the imp. You've played dnd a time or two, and figure the little creature won't be able to do too much to you. She nods, and begins to chant. The lights gutter low, and there's a rush of wind with no visible source, bringing the scent of oranges and smoke.

"Speak witch." Comes a sudden voice from behind you. You glance around and see a small figure there. Less than five feet tall, though with a face that is simultaneously young and impossibly old. She has bright red skin, scarlet in color, with hair the color of coal, draped around a pair of horns which jut from her head. They're quite small you note, almost cute. She's completely nude, with small breasts, an A cup at most. Her nipples are a darker shade of red, and come to points. As your gaze drops, you take an involuntary step back, and run into an invisible wall at the edge of the circle. Her dick is ten inches in length and as thick as your wrist, grotesquely large on her small frame.

"This is the mortal you were promised Irichtys. You are free to sport with him, but nothing permanent, and no deals. Just fucking." The wizard says.

The imp, Irichtys apparently, fixes her eyes on you. They're a blue so pale it edges into white, and glow from within in the dim room. She grins at you, and you suddenly understand the origin of the descriptor "impishly."

"Well then mortal, let us sport." She nods at you, then suddenly barks "Down on your hands and knees! Now!"

There is unexpected venom in her voice, and you hurry to comply. For all her small size, you can't help but do as she says. You quickly get down on your knees, and she walks to stand behind you.

"Every apprentice who first learns a spell thinks its fun to summon up and imp for a quick fuck, to use my ass as rough as they please, just cause I can't stop them. Well now I have a mortal of my own. Are you ready?"

You shake your head nervously, and she laughs, "That's the spirit!"

With a sudden thrust, you feel the head of her crack open your ass. She's big, very big, and you cry out in pain as your ass struggles to accommodate her monster. She smacks a hand on your ass hard and gives another thrust.

"Come on, you can cry louder than that! Scream for me bitch, take it all!"

She thrusts again and again, and your arms give out. You collapse your head to the cool stone floor as she shoves her cock roughly into you again and again. Your world constricts, shrinking to the pain in your ass and the laughs and yelps of glee from the imp abusing it. She hammers away for a long while, then suddenly pulls out groaning, and shoots long ropes of fiery cum across your back. As her hands leave your hips, you collapse fully to the floor, utterly spent.

"You think you're done bitch? I'm just getting started!" You try to protest, but her cockhead finds your ass and shoves right back in, picking up where she left off. Your protestations turn to squeals as she's being even rougher now, your ass stretched enough from your first round to give her proper access for a rough fuck.

"Yeah bitch, I'm going to go all night!"

She isn't lying. Irichtys fucks you for hours, cumming on you a dozen times, and forcing you to take it in every position she can imagine. By then end you're lying in a pool of her cum, completely spent and insensate. She gives you a final decoration across your face, then turns back to the wizard.

"Thanks witch, call me any time to fuck an ass like this!"

She disappears much as she came, and leaves you alone again. You struggle to stand, but find your legs don't respond as they should.

"Oh dear," the wizard says, coming to stand next to you. "Well I did warn you, but she was more enthusiastic than I anticipated. Here, I'll bring you to the tavern, and get you a room for the night. You'll be right as rain tomorrow.

You aren't sure about that, but she collects you easily, and brings you to a warm bed.