Magic of course.

“Fuck me till you are tired, then take a nap.” The second you say it you can't help but think you should have left the first part out, but the demon's weapons drop to the ground and he pounces on you like a rabid beast. In an instant you are hoisted off of the ground, he takes your legs in his lower arms, your arms in the upper. You are then essentially folded up. He turns you around, lifting your legs till they are across your body and tight against your chest. Your arms are then pulled around them till you are basically hugging your legs. Then he takes each of your hands and holds them tight, a loop of strong metal cord is then wrapped around each wrist and your arms are tied behind your back tight. As a nice tight bundle you are then held up, back to the demon and lowered onto his ever swelling cock. You can't see it, hell all you can really see are your legs and the wall, but you definitely know his cock has grown and is pressing against the opening of your cunt. “Ooh. Wow that is thick.” You gasp as the head finally is **** in. The pressure is intense, and you find you are holding your breath as he pulls you down onto him. If it wasn't for the fact that you can tell you are going down, and your gasp for breath seems to be pushed out of you, you wouldn't even be sure he was really getting it in. Suddenly he drops to his knees, falls forward, and smacks you on the hard ground. With all four hands he pushes you down against the ground holding you absolutely still. Then you feel his hot breath on your shoulders, he grips your neck with two hands, your arms with the other pair, and drives into you finally getting it in all the way. His massively thick rod was clearly made to fuck something far less delicate and far larger than you, but none the less he then begins fucking you in short strokes, powering down on you. The more he does, the harder he thrusts, the more the feeling of warmth fills you. The aches of being impaled, the shortness of breath, the strain on your muscles all washes away with each stroke. Your amazingly evil body warms to the touch, the pounding invigorates you. Without even knowing it happened your hands are pinching your nipples, having snapped the cord effortlessly. He keeps driving and pounding, and your hooves slap the ground. Driving back into him with each thrust you rise up first on hands and feet, then just standing bent over, hands clutching your breasts, not even needing anything more than the muscles in your legs to keep you going slamming back into the four armed monster. His power is still ever present, and you can feel his hands working over you, hell he is basically trying to strangle the life out of you, but it doesn't matter, the fucking is incredible, and you are stronger for it. Then he does something that catches you by surprise. He lets go, not only does he let go with both hands, he lets go with a spray of cum that would surely fill a gallon jug. As it is your stomach seems to grow for a slight second, then you are blasted forward, nearly falling on your face, only catching your self in the last instant.

Rolling over, chest heaving, blood pounding in your ears, with a toothy demonic grin smiling up at the spent demon. For a second you are sure he is going to do more, but instead he simply flops down, turns around twice, and flops into a cute little ball like a cat. “Awe. What the fuck, that is adorable.” Remembering your magic, you carefully perform the ritual that draws forth his seed from within you. It goes much faster this time, and the black bead that pops out is less than half the size of the ones you got earlier, despite the increase in volume. “Weird. Ooh, the size must indicate how powerful the donor is. You must be a weaker little thing aren't ya?” You ask the sleeping monster. Just then you get a flash of inspiration, something in you, something wicked leads you to believe if you did the magic of the ritual over the sleeping demon, you think you could use the monster himself to make one of the black beads from it's demonic essence. “Fuck that is evil.” You with a gasp. Then again you are a devil.