Even though your voice is barely a whisper, and the unicorn seems very far away, he lifts his head up and turns. His pale eyes focus instantly on you, rooting you to the spot.
You want to run, but the sight is so wonderful as the unicorn approaches that you find that you can't. You feel a surge of fear though your body as he comes within steps, but fades when you realize that there is no anger in his stance, no sense of aggression. He seems to exhude an almost calming sensation, but also a bit of sadness.
Your mind suddenly fills with thoughts, not really words, but more concepts and ideas. It takes you a few moments to sort it out, but you realize quickly that it's the unicorn communicating with you! You try to follow along, but are quickly overwheled and fall to your knees as your mind swims.
The unicorn takes a step back and the thoughts slow to the point that you can grasp them. The reason that the unicorn feels sadness is that you weren't supposed to be here! No human is allowed to gaze upon a unicorn, you gather, for reasons he either can't express or doesn't know.
He manages to communicate that you have three choices, none of them good. You can choose to die, which the unicorn will carry out painlessly even if he doesn't want to do that. You can choose to be transformed into a random forest creature so you can't communicate the existance of the unicorn, or you can choose to become a unicorn yourself!