Author's Note: I have no claim over Buffy and Co., nor over Harry and crew. They belong to Joss Whedon and JK Rowling, respectively. Please read and review!

Buffy spent the rest of the week exploring the nooks of the castle or training dungeon. Snape looked more unpleasant each time she saw him. She still wasn't sleeping well but she was holding it together. That wasn't new. She'd been doing that for years now.

The staff, with the exception of Professor Snape, was very kind to her. Though she wasn't witch, being the slayer meant there was some magic in her blood so should could understand the basics of spells, eve though she couldn't cast them. They explained the different branches of magic to her.

"Transfiguration is using magic to turn one thing into another. Wizards who can turn themselves into animals are called metamorphmagi." Professor McGonagall demonstrated by turning herself into a cat. Charms, Flitwick told her, was the art of enchanting objects.

"Defense Against the Dark Arts is just what it sounds like, though the new teacher hasn't arrived yet," the gnomish man said. Finally it was September first and the castle was hopping with activity. Mr. Filch was cleaning the last of the paintings and Hagrid was helping with the decorations. All of the teachers were sequestered in their offices, making last-minute changes to their lesson plans. Then the torrent of students poured into the great hall for dinner. Buffy had already eaten and didn't feel like joining the kids yet, so she waited in Dumbledore's office, making small talk with the many portraits. She sat down as she heard someone coming. Professor Dumbledore entered with a wiry, dark-haired boy in tow, who sat in the chair next to her. She glanced at him and could see a lightning-shaped scar above his glasses.

"Harry, I would like you to meet Ms. Buffy Summers. She will be joining us at Hogwarts this year, all the way from California."

"Are you like an exchange student or something?"

"Not exactly. Harry, Buffy is the slayer. Do you know what that is?" Dumbledore asked.

"Isn't it supposed to be a girl who hunts and kills demons and vampires? I always thought that was a myth."

"No, it's not a myth. I asked Buffy to join us this year to help protect you. Harry, you are more courageous and resourceful than many adult wizards, but I think it's important that we arrange for additional protection. Voldemort seems to be preoccupied with you, not to mention that Sirius Black is on the loose, so we need to take precautions. Buffy here will be escorting you while you're at Hogwarts. Now please, I know you don't want the extra attention but Buffy will not be interfering with your life save to keep you out of trouble. She will merely sit in on your classes and quidditch practices. And she already knows about your invisibility cloak, though she'd probably find you even if she didn't. I know you did not ask for all of this but I'm asking you to cooperate."

Harry wasn't thrilled with Dumbledore's proposal. As if people didn't gape at him already. And no offense to her, but she couldn't weigh more than 100 pounds soaking wet, so he couldn't really see what good she'd be able to do. She claimed to be the slayer, but he had serious doubts about that. The look on Dumbledore's face, however, told him he didn't have much choice.

"Fine, but she's not going to hover over me all the time, is she? I get enough grief as it is."

"No, 'she' will keep respectable distance. Don't worry, I'm really not here to disrupt your life at all. I'm just here to be available to kick some butt if the opportunity ever comes up," Buffy told Harry.

"Opportunity?"

"Bad choice of words maybe."

Buffy's duties started as the new term began. Harry grudgingly introduced her to Ron and Hermione but he didn't tell them about her alleging to be the slayer, as Dumbledore said she was. He wasn't too keen on having her around, but eventually they got used to each other. She never bothered him during class (she usually elected to sit in the back) or quidditch practices. She even helped Oliver design new plays. And Buffy had grown fond enough of Harry (which was about as much emotion as she was able to muster up for anything these days).

Besides escorting Harry around, Buffy didn't have much to do. She attended classes she didn't have to listen to, where they gave homework she didn't need to turn in. She found Harry's classes a lot more interesting than anything she'd taken before, except for maybe Professor Snape's class. It was a pity, too because she found potions to be the most fascinating. Buffy's world was grounded by things she could see and touch, even if they were supernatural. She had to be able to touch her enemies to beat them, which was why losing her mom to cancer was so painful.

It was also why classes like charms and divination were beyond her. But she understood potions. All you had to do was measure out the proper ingredients and follow directions. Crush, kill destroy, easy as pie. Professor Snape, however, tried his best to make sure she didn't start enjoying herself. He almost never spoke to her directly, but instead made thinly veiled insults while he badgered Harry.

"So why does Snape hate you so much?" she asked him after a particularly venomous potions class.

"He and my dad were at Hogwarts together and they hated each other, a lot like me and Malfoy. My dad was popular, good in class and at quidditch and Snape wasn't, so I think he was jealous. My dad saved his life at some point and Snape hated owing my dad anything," Harry said as they headed back to the common room.

Meanwhile, Buffy still wasn't sleeping well. What few hours she managed to catch were filled with awful dreams that left her covered with sweat. The worst part of the job, however, were the Dementors that were stationed around the grounds. She'd never encountered them directly, but she could tell whenever she was even near one. Her mind went cold and dead, and she felt like someone threw a freezing wet blanket over her. Sometimes she could even hear the voices of Dawn and her friends screaming in her head. She wondered if that happened to everyone. Dumbledore had explained what the Dementors did, but no one else seemed to be having that reaction. They made her feel worse than she had ever felt before. After one horrible near-miss, she decided to talk to Dumbledore about them.

"Sir, could I talk to you for a minute?" she asked.

"Certainly Buffy, lets go to my office. He led her back to his room and offered her a seat. "Now, what can I do for you?"

"well, it's about the Dementors. Every time I get near one I start hearing and seeing things. It feels awful. At first I thought they effected everyone like that, but now it seems like it's just me. Why is that?"

"Dementors are among the foulest creatures on Earth. They feed on emotions and leave a trail of despair and insanity in their wake. They effect you worse than most because you have memories in your past that others don't. You've experienced some horrifying things that people could not imagine. Those experiences leave you more vulnerable than most. You are wrong about one thing, though. Our own Harry Potter has the same reaction for similar reasons."

"Is there anything I can do to fight them?"

"There is a powerful spell that will repel Dementors but it's very advanced magic that many adult wizards cannot manage. I'm afraid for you there is no real defense, save for avoiding them whenever possible. I'm sure to you that seems like cowardice but I believe that is the only thing you can do. If you were a witch, perhaps it would be possible to teach you the patronus charm, but I'm afraid that's not an option."

Just then, the door swung open and Professor Snape stormed in. His eyes narrowed maliciously as he saw Buffy. "Ah, Severus, you're right on time. Would you mind giving Ms. Summers and I just another minute? Thank you." Snape sneered again as he left the room. "Like I said, Buffy, I believe it is in your best interest to simply avoid the Dementors. They are not susceptible to physical attacks so you will not be able to fight them. Now unless there is anything else, I must meet with Professor Snape" He stood with a smile and gestured toward the door. She passed Snape in the hall. He looked positively murderous. Boy, she thought, if looks could kill even a slayer would be defenseless.