Dog

Your legs are becoming longer and your feet more angular but you still have your toes he let out a groan as the tip of your cock begins to sharpen a new sharp teeth begin to grow in your muzzle.

It's quite surreal, feeling the muscles shift around you is to ruthlessly plough into your sister from behind. You can hear her moaning and now an additional sound coming from both of you are whining barking noise.

As your nose becomes black and the smell of arousal becomes even stronger it's obvious that you're becoming some kind of dog and the fur that is rippling across your body seems to sing from the sudden stimulation.

You keep thrusting, a little deeper each time as your body loses any trace of human on the outside your new knot locking you inside and preparing you to seed your perverted scientists sister.

"Wait! Marky no! Whatever you do don't..." Stammered Alice starting to yell with sudden urgency.

"You mustn't... If you do it inside me... I'll change too!" She screamed.

But it's too late, your knot is already locking you together, you can feel the pressure building as your first canine orgasm begins to overwhelm you.

You could hear Alice crying out and beating the floor but you're not sure whether it's from pleasure something else.

You can see Alice's hand reaching for something, the gun? You wonder what she is trying to do but as pleasure overwhelms you you're suddenly aware of flash