"I'm sure you're wanting a bit of explanation, right?" One of the unicorn mares was now eye-to-eye with you, although her face was upside-down from your viewpoint. You felt Aqua start moving again, sending shivers of pleasure down your spine. "Every mare has something called an estrus cycle. To put it bluntly, we have periods of heat where our body forces us to copulate," she said while waving a hoof at Aqua.