The mare walks toward you, stopping with the base of its chest between your legs. "You will have to relax, human. This may be a little painful..."

With that the mare slid its tongue across your cock, quickly stirring you into an aroused state. "Wh-what are you doing?" You asked, but the mare simply looked up at you in a frustrated manner. "I said: you're going to have to relax. Now lie back down."

You were still worried, but out of a fear of angering the mare, you did as you were told. You feel the mare's gentle caresses begin again, an before long, you find that your breathing has become heavier. Your body wants to engage in intercourse, and despite your precarious situation, you are having to fight hard not to simply give in.

Then, without warning, the mare stopped licking your visibly hardened cock and instead slid it into her mouth. You could feel the gentle caress of her cheeks as she began making sucking motions. You closed your eyes, drifting unwillingly into an erotic state of calming. 'What the hell is going on here?' you thought to yourself.

The mare's tongue undulated across the base of your cock, wrapping itself around and around your member. You felt fantastic. A rythmic motion on your cock signaled that the mare was bobbing her head on your dick. You began to feel a strange pressure on your cock, as if the mare's throat were shrinking.

The vigorous exercise continued until you could take it no longer. Your body lurched a bit and a repressed grunt escaped your mouth as you unloaded into the back of the mare's throat. Every muscle in your body tensed, desperately clinging to the immense pleasure you were feeling, hoping that the moment would never die. Then, as you laid back down with a sigh, you felt a very strange motion. The mare had begun sucking on your cock again! You opened your eyes and looked up over your chest. You could see the mare's head at the apex of your legs, still bouncing up and down, but something was different. Her neck was becoming bulged, as if something were...something were growing inside of it.

Then, it dawned on you, the mare's throat hadn't been getting smaller, your cock had been getting larger! You stared in disbelief as the swell in the mare's throat continued to grow, and it didn't look like it was going to stop.

Just as you were sure that the mare's throat would burst, she slid her head of your cock, gasping. There, lying at the base of your waist, was a monstrous distortion of the member you had once called your own. Your cock had grown at an intense rate. You couldn't quite tell, as you obviously sill had an erection, but it must have been at least a foot and a half long and about three inches wide at its base.

The mare struggled to regain her breath. "Slave girl...