I don't own Harry Potter. This is an AU of Harry's fourth year. There's no Triwizard Tournament and thus no re-birth of Voldemort. Also, keep in mind that I have an account on Hogwarts Extreme and that Lunastar1981 is my username there, so no report of my copying this story.

Chapter One- The Touch

Harry stared at the beautiful golden unicorn foals that had been brought to Care of Magical Creatures class for the fourth-years to study. It was unusual for Hagrid to bring something non-dangerous to class. Harry appreciated it, seeing as how the foals interested him in a way he couldn't readily explain

He stepped over and grab a couple of sugar lumps from a bucket that Hagrid was holding. He waited for his turn to fee the foals and when it came, he felt a trembling inside him that he identified as excitement. He held out a lump to the nearest foal who lipped it out of his hand. Harry smiled at the gentle touch and patted its neck gently. As he lifted his hand, Harry felt an urge to…neigh and start running through the forest like a horse…or a unicorn. The urge passed as quickly as it had come and the rest of class passed by uneventfully.

"That was an excellent lesson," Hermione said as they headed inside for lunch. Harry nodded, his mind still on the weird urge he had felt. Why did he desire to run like a unicorn? It didn't make sense. He shook his head slightly. He didn't need to dwell on it. He had an enjoyable lesson, simple as that.

He ate lunch before heading to Divination with Ron. He didn't enjoy Divination particularly this year as it was a double period on Mondays. Today would be no different and he was almost correct. He was halfway through the class when his head throbbed. He put a hand to the throb casually so Trelawney wouldn't see it and attribute it to the vibrations of her tower.

The moment the bell rang, Harry said to Ron, "I'm going to see Madam Pomfrey. Go ahead to dinner without me."

"What are you going to Pomfrey for?"

"Slight headache," Harry managed to say as he stood and felt slightly dizzy as well. He climbed down the ladder, down the tower steps, and reached the floor the Hospital Wings was located. He got to the doors and pushed them open, staggering slightly and a hand to his head.

Pomfrey came out of her office when she heard the door open and saw Harry stagger in. She went to him and eased him onto the nearest bed. "What's the problem, Potter?" she asked, all business.

"Head hurts and I feel dizzy," he said thickly.

"How long have you felt this way?" she asked as she felt his forehead and then his wrist.

"It started halfway through Divination. I started feeling dizzy after class."

"Anything else unusual?" she asked as she started running her fingers over his head and down his back.

"Well, before lunch I got a weird urge to run through the forest…almost like a unicorn."

"Well, nothing I can do about…what is this?" she said as her fingers reached the base of his spine and felt a bump. Harry knew this because her fingers pushed on it slightly. He felt her lift his shirt and pull back his pants. "What the-?" she gasped.

"What is it?" he asked, alarmed.

"You look like you're growing a tail."

"A…tail!?" Harry put a hand behind him and his fingers felt a short growth of hair beneath his fingers. "What kind of tail?"

"It looks like a horse tail and its bright silver, so it more closely resembles a unicorn tail."

Harry groaned as he grasped his throbbing head. Pomfrey frowned. "I'm going to keep you at least overnight, Potter." She tossed his some pajamas and drew curtains around him to give him privacy. Harry removed his clothes, his hand straying to his back. It hadn't changed; a short growth of hair that according to Pomfrey was silver like a unicorn's tail. Why am I growing a tail? he wondered as he got dressed. How did this happen? He climbed into bed as Pomfrey pulled back the curtains and presented a dinner tray.

"I will be speaking to the headmaster about this," she said. "He may know how this happened and why." She pressed a cup into his hands. "This'll take care of the headache and dizziness."

"Thanks," Harry said gratefully, drinking the potion and then starting on his dinner afterward. His head had stopped throbbing and his dizziness had faded. Ron and Hermione were going to come by to see him and he knew they would be just as shocked as he was about the tail.

Harry laid on his side facing the ward's doors. He found lying on his back difficult because the tail was only a bump, which he knew would probably grow longer; but how long was the real question. The doors opened and his friends came rushing in and to his side.

"Harry, we were worried when you didn't come to dinner," said Hermione.

"Yeah," Ron agreed. "You said it was a headache."

"It was," Harry said. "But Madam Pomfrey found something at the base of my spine." He nodded over his shoulder. Ron and Hermione moved to the other side and Harry pulled the pants down slightly.

"Is that…a unicorn tail?" asked Hermione, sounding stunned.

"Yeah," Harry answered, pulling his pants back up and his friends came back into his field of vision. "I have to stay overnight and Dumbledore's gonna be told. He may know why this happened."

I sure hope he knows why and how. Maybe even how to undo it, he thought to himself.