It's Kathryn on his family's front porch.
"Hmm," she said, staring at him happily. "You're coming along nicely," Kathryn added, while stepping inside and locking the front door behind her.
"What do you mean?" asked Nate. "Did you--"
"Yes. I'm a witch, and you're under my spell," admitted Kathryn, as she started to unbutton her blouse seductively.
"What's happening to me?" he asked, as his groin started to ache.
"You're turning into a satyr," she replied, as Kathryn stripped down to just her sexy underwear.
"Why?" asked Nate, feeling his pants get tighter, and not just because of the beautiful sight in front of him.
"First off, you picked the shape when you chose the cookie. Secondly, this will certainly cure your boredom," she answered, while rubbing her hands against Nate's pants. "Besides, the way the world is nowadays, there is definitely room for improvement. Now then, before you progress any further, we better get you out of these clothes," added Kathryn, while unzipping his pants.
Nate looked down as Kathryn undressed him. Even without whatever else was going on, he had to admit that her actions were quite arousing.
Without prompting, Nate finished stepping out of his clothes that were now lying on the living room floor while he removed his shirt. He looked down and saw his manhood was growing much larger than he ever thought possible and was being surrounded by a furry sheath.
"There is a special energy released during a satyr's very first time, especially if he was a virgin in his previous humanity."
"How did you know--" began Nate, but the witch ignored him and continued speaking.
"I not only want to welcome you into satyr-hood, but I also want to be the lucky recipient of your first experience to increase my own powers," revealed Kathryn, as she resumed stroking his growing penis.
"Ohhh, y-yess...." said Nate, as he hastily removed Kathryn's panties and backed her up against the couch, not noticing that his feet were now hooves.
He didn't care that there was a tail starting to appear above his rump, or that his ears had completely become pointed as two horns began to sprout out of his forehead.
As fur continued to grow all over the lower half of his body, all Nate was concerned about was the growing fire within his loins, and Kathryn's willingness to quench it.