AN:

1. This is a Kuro fic first before it's a HP fic. I'm putting Ciel and Sebastian in the HP universe and so, I'll be doing everything from Ciel/Sebastian POV and tell the story of how the various events affect them.

2. I try to follow the book, but some things need to be altered because Ciel is there. I'm also skipping a rather big chunk of the book.

3. Harry & co. would be OOC to accommodate Ciel.

4. This is a SebaCiel fic at heart and Ciel is a demon here. I have to invent a few things, but I hope they turn out okay.

It was ten o'clock in the morning and Ciel Phantomhive, former earl and current demon, was sitting in his library with a book. So engrossed he was in his book, he jumped when he heard someone – or something – tapping on his window.

Ciel's head whirled around to take a look and blinked at the sight. A brown owl was pecking at his window glass insistently and it was holding something in its feet, some sort of a... letter? Intrigued, he put down his book and slowly made his way to the window, fully expecting the bird to fly away as he approached, but it remained perched on his windowsill.

Ciel opened the window and the bird flew into the room and dropped the letter on the desk before it perched itself on top of a reading lamp.

For a few moments, Ciel just stared at it, unsure of what he was supposed to do. Then he moved to the desk and picked up the envelope.

To: Mr. C. Phantomhive & Mr. S. Michaelis

7 Knights Street

London

Ciel turned the envelope in his hand, but saw no sender. A soft hoot made him looked up and he saw the owl was still perched on top of the lamp, looking at him somewhat expectantly.

"Sebastian!" Ciel called.

The door to the library was opened a few seconds later and Sebastian entered the room. He raised his eyebrows as he surveyed the sight before him. Ciel was standing by the desk, the window was wide open, and there was an owl perched on top of the reading lamp.

"Do you need anything, Young Master?" The butler asked.

"Not me. But I think it wants water or something." Ciel pointed at the owl.

Sebastian turned to the owl. "The owl, sir?"

"Yes, Sebastian, the owl." Ciel said exasperatedly. "Now, don't just stand there. Get it some water so that it may leave."

"Very well." The butler left and came back a minute later with a small bowl of water. He put it on the table and the owl pecked at it a few times before flying away.

"May I know what was an owl doing in here?" Sebastian asked.

"It delivered this letter. And it's addressed to the both of us." Ciel said, showing him the envelope. He reached for the letter opener and broke the wax seal at the back before taking out the content, a letter written on a parchment paper.

Sebastian moved to stand behind his mate to read over his shoulder.

Dear Mr. Phantomhive & Mr. Michaelis,

My name is Albus Percival Wulfric Brian Dumbledore. I'm the headmaster of Hogwarts School of Witchcraft and Wizardry. I'm writing to you to inform you that I will be calling on you this afternoon to discuss a very important matter. I apologize for the short notice, but this is a rather urgent matter. I shall be there at one o'clock in the afternoon.

Signed,

Professor A. Dumbledore

"School of... what now?" Ciel asked out loud.

"Hogwarts..." Sebastian placed his fingers under his chin. "There are several magic schools in the world and I've heard of this one. If I'm not mistaken, it was built some time in the late 900s."

"Magic school? People go to school to learn magic?" Ciel asked.

"Yes, sir, I believe so."

"But who'd be going to a magic school?"

"Magicians, of course." Sebastian told him. "Now, since we're having a guest this afternoon, I shall start preparing for his arrival. Do you need anything before I go?"

"No." Ciel said, still reeling from the information.

"In that case, I shall go to the market. I will be back within the hour." Sebastian said and left with a bow.

Something occurred to Ciel. "What does the headmaster of a magic school want with a pair of demons?"

When the doorbell rang at exactly one o'clock, Sebastian opened it and found a man standing at the door. He was a tall man with a long, silver beard and a pair of twinkling blue eyes. He wore a pair of half-moon glasses and a light grey robe.

"Good afternoon." Dumbledore greeted the butler.

"Good afternoon. Professor Dumbledore, I presume?" Sebastian said, studying the man carefully. In his long life, he had had a few encounters with witches and wizards and he found them to be quite full of themselves, if not downright arrogant, just because they could turn a turtle into a teapot. "My master has been expecting you." He stepped aside to let the man inside and led him into the living room, where Ciel was waiting, sitting on his armchair, holding the letter in his hand.

The former earl got up at their guest's arrival. "Good afternoon. I'm Ciel Phantomhive and that's my butler, Sebastian."

"Albus Dumbledore." Dumbledore introduced himself. "Thank you for accepting my calling card, gentlemen."

"Of course. Please take a seat." Ciel said and gestured at the sofa across from him.

Sebastian prepared the tea and refreshments and served them before taking his place behind his master's chair.

"How can we help you today, Professor Dumbledore?" Ciel asked.

"I'm here because I have a request." Dumbledore said. "Have you heard of Hogwarts?"

"I didn't even know that magicians exist before today." Ciel admitted. "But I believe my butler, in his own words, has heard of it."

"Is that so?" Dumbledore turned to look at Sebastian. "You look quite young, but I suppose, with your kind, it's impossible to tell."

"So you do know what we are?" Ciel asked.

"Yes. I have done my research and I believe that you two are the only ones who can help us." Dumbledore said and took a bite of his biscuit. He made some appreciative noises. "This is really delightful."

"Sebastian makes the best sweets and tea." Ciel said.

"I'd have to agree." Dumbledore nodded.

"You are too kind." Sebastian said with a slight bow.

"You're here because you need our help?" Ciel prompted.

"Ah, yes. You see, something is coming. Something dangerous and evil. It will bring forth chaos and destructions, not only in the wizarding world, but also in this world."

"Something evil is coming to destroy the world and you're asking for help from demons?" Ciel asked. "I do believe you might have been mistaken in presuming our nature."

"But that's exactly why I'm here." Dumbledore said with a smile. "As I said earlier, I've done my research and even though the two of you are what you are, you've been living among us for decades and not once have you ever caused any chaos or destruction. I believe that if mankind becomes extinct, you will not benefit from it either. We, magicians, even with all our magical abilities are still humans, while you are not. If anyone could help us, it would be you."

Ciel leaned back in his chair and regarded the man carefully. "You have a point. But you know that a demon's service is not free, yes?"

"Yes." Dumbledore said. "I will pay for it with my... life."

"Your soul." Ciel corrected. "If we were to agree to help you with whatever this is, we want your soul."

"Of course." Dumbledore agreed. "But I only have one soul to offer, mine." He looked at the two of them.

Ciel got up and walked to Dumbledore. He leaned close to the man's face and took a whiff. "Your soul will be enough. It is delectable. Full of sorrows and oh so righteous... We shall enjoy it for sure."

In all his life, Dumbledore had never had any dealing with their kind before. He could feel a shiver run down his spine at the young demon's words and he briefly wondered if he had done the right thing by coming here, or had he doomed them all by involving these creatures? When Ciel straightened up, the wizard let out a breath that he didn't know he was holding.

"Do we have a deal then, Mr. Phantomhive?" Dumbledore asked.

"Depends. We don't even know what is it that you require of us. Tell us what you want from us and then we can discuss the terms." Ciel said and sat back down.

"There is this wizard who called himself Voldemort..." Dumbledore started. He proceeded to tell them about what Voldemort had done and what had happened to him.

"And you have reasons to believe that he's back?" Ciel asked. Despite himself, he found the situation to be intriguing.

"Not yet, but he will. And we have to be ready for it." Dumbledore said. "Harry Potter, the boy who survived him, is under our care now at Hogwarts, but there's only so much that we can do to protect him."

"You're mistaken if you think that we'd be interested in playing babysitter to a teenage boy." Ciel said.

"No, not at all. I want you to come with me to Hogwarts and fight alongside us when the time comes." Dumbledore said.

"Or..." Ciel gave him a counteroffer. "You could just tell us where we can find this Voldemort fellow and we can get rid of him. Thus, you won't have to worry about him returning at all. You'll rid yourself of him, we'll get your soul, and everyone is happy,"

Dumbledore shook his head. "As per now, nobody knows where he is."

"Then wait until he returns and come back to us." Ciel said.

"That would be too late. I believe that when he finally returns, Voldemort will not be alone. He will have an army with him, his followers, both old and new." Dumbledore said.

"Young Master, if I may..." Sebastian spoke up.

"What is it?" Ciel asked, turning to his mate.

"I think it would be beneficial for you to attend this magic school." Sebastian said.

"What on earth are you prattling on about?" Ciel glared at him. "I'm no magician."

"You are not, but you're young and your magic is still developing. It would be good if you could learn more about your magic, and magic in general, in a structured learning environment, like in a school."

"I thought that's your job?" Ciel asked, raising his eyebrows. "Or are you saying that you're not capable enough to teach me?"

"Oh, I am more than capable, I assure you." Sebastian said. "But being with others might motivate you to learn even more, not to mention, you will gain an experience that you would not get from me alone."

"Such as...?"

"Such as being among your peers and learning from them."

"I do not need that!" Ciel said. "What are you playing at, demon?"

"Ah, my lord, it has been a while since we played any good game, has it not?" Sebastian asked. "At the very least, you'll have something to do to occupy yourself."

Ciel thought about it. "Hm, you're right. It's been a while and this sounds like a fun game."

Dumbledore sat there and listened to the two of them conversing. If he had any doubt about what these two were, he didn't have it anymore. After everything that he had told them about Voldemort, about the horror that the madman had brought upon the world, they were treating this as a game?

"Professor Dumbledore," Ciel said, turning to face the wizard. "Before we agree to help you, there are a few other things that we want to discuss with you. First, tell us more about your school."

Dumbledore did.

"I think that the best disguise for you is to be one of our students." He said at the end of his explanation.

"I agree." Sebastian said, a little too cheerfully for Ciel's liking.

"Quiet you. You're just doing this for your own amusement." Ciel said. "But unfortunately, I must agree as well. Given my… appearance, it would raise suspicion if I go there, but not enrolled as a student."

Dumbledore nodded. "Excellent! As for Mr. Michaelis… Unfortunately, he looks a little too old to be a student …"

"Hear that? You're an old man." Ciel sneered and Sebastian just sighed. "He'd come with me as he is, my butler."

"We don't encourage students to bring… servants." Dumbledore said.

"You see, Professor, he goes where I go and if I'm going to this school of yours, then he's coming with me, or the deal is off."

"How about a teaching position?" Dumbledore asked. "You must've had some experiences. Although we'll have to think of something as we don't have any vacancy right now…"

"No." Ciel declined. "He's my butler and that's what he'll be. Also, I'm not sharing a room with any other student. We want our own accommodation. These are the terms if you wanted to engage our service. If you can't fulfill them, then I regret to inform you that we won't be able to help you."

Dumbledore thought about it. "You want your own private accommodation and Mr. Michaelis will be coming with you as your butler. In turn, you will be a student in our school and when the time comes, you will help us fight Voldemort. Is that correct?"

"Let's not forget about our reward, shall we? Once it's over, we want your soul as our payment." Ciel said.

"Very well, I accept your terms." Dumbledore said. "I heard that you would form a… contract of a sort?"

"Not this time." Ciel said. Forming a contract would give Dumbledore power over him and in turn, over Sebastian too, and Ciel didn't trust the wizard enough to give him that kind of power as he wasn't familiar with their kind. So he decided to play it safe this time. "I shall allow this one to remain as a deal without a contract. But make no mistake. If you tried to cheat us of our reward or failed to fulfill your end of the bargain, Voldemort will be the least of your problems. Do we understand each other, Professor?" He let his eyes shift into their demonic shade.

"How do I know that you will fulfill your end?" Dumbledore asked.

"You don't." Ciel said. This was why he'd allow this one to not be a contract. If this thing was more troublesome that it was worth, they could just drop the whole thing and leave, without any consequences nor anything holding them back.

"I understand." Dumbledore finally said. "It's a deal."

"It's a deal." Ciel nodded.

"Do you think it was the wrong move not to make a contract for this?" Ciel asked his butler as they lay in bed together.

"What made you say so?" Sebastian asked as he ran his fingers through Ciel's soft hair.

"It's the first time that we do this kind of thing, not making a contract but we're promised a soul in the end. Without the contract to bind me to him, if something went wrong, this whole thing would be a complete waste of time and efforts." Ciel said.

"Why didn't you make one then?"

"I don't trust him, or his kind. I could feel his magic. It's strong, extraordinarily so. I don't want to give him any more power. If he could order me around, he could, in extension, make you do his bidding. I don't want him to have that kind of power, your power."

"You did the right thing by not making a contract." Sebastian said. "Witches and wizards are humans still and they possess human attributes, including their arrogance and greed. Unlike normal humans, they know what magic is. They have tasted power and giving them a control over demon's power could end up in disaster."

"We have to be careful then." Ciel said. "If anyone were to find out, it could put us in danger."

"You know I will protect you at all costs."

"I know." Ciel said and kissed him. "I love you."

"I love you too." Sebastian returned.