Hey all! This is my first ever Fairy Tail / Harry Potter crossover! To be more precise, it's a crossover of Harry Potter and the AU Fairy Tail I created in 'The S-Class Mage'. I hope you enjoy it!

IMPORTANT: I CREATED A FACEBOOK PAGE WHERE ANYONE WITH QUESTIONS ABOUT 'THE S-CLASS MAGE' OR 'WHEN WORLDS COLLIDE' CAN ASK THEM. THINGS ABOUT CHARACTER BACKSTORIES, CHAPTER PROGRESS, THE TIMELINE, ANYTHING! EXCEPT SPOILERS. I CHECK IT SEVERAL TIMES A DAY, SO PROMPT RESPONSES ARE GUARANTEED.

LINK IS ON MY WRITER PROFILE.

Disclaimer: I do not own Harry Potter or Fairy Tail.

After their decision to wait, Harry and Meledy told the other three about what Riddle's diary had shown them. They regretted it rather quickly since the others, especially Hermione, made them re-tell the event over and over, following it up with long, circular conversations which never got anywhere.

"Riddle might have got the wrong person." Hermione mused. "Maybe it was some other monster that was attacking people."

"I know, Granger." Meledy didn't even waste her irritation anymore. "I heard you say that six times already."

"We always knew Hagrid had been expelled." Harry added. "And the attacks probably stopped after that. Otherwise Riddle wouldn't have gotten that award."

"Eleven times."

"Riddle does sound like Percy..." Ron tried a different method. "Who asked him to grass on Hagrid, anyway?"

"Hey, that's a new one!"

Wendy sighed. "But the monster killed someone, Ron."

"Even you, Wendy?" Meledy shook her head. "Nine times."

"And Riddle was going to go back to some Muggle orphanage if they closed Hogwarts." Harry ignored Meledy. "I don't blame him for wanting to stay here..."

Wendy hesitated. "Didn't you run into Hagrid in Knockturn Alley, Harry-san?"

"He was buying a Flesh-Eating Slug Repellant." Harry explained quickly.

After a long pause, Hermione spoke up. "Do you think we should go and ask Hagrid about all this?"

Meledy snorted. "Yeah, no. I can't see any of this being good material for casual conversations."

And with that, the group decided to wait until further developments. Days passed and no attack occurred, nor did Harry hear any more strange hissing. People's suspicions about him were slowly fading away and the Mandrakes were growing and close to maturing.

And then came Easter.

"You will now select additional courses that you will attend, starting your next year." Acting Head of Gryffindor Erza Scarlet announced as she handed out lists to the second-years. "You are required to select at least two subjects, but you may choose more if you wish and I will do my best to arrange your schedules accordingly. You are not allowed to drop any of the subjects you are currently studying. Each subject is unique and could lay the groundwork for your eventual career. I implore you all to think carefully about where you see yourself in the future and which lessons you think will aid you most in reaching that goal. If you wish to inquire about any specific subject or any other matter regarding the selection process, feel free to ask. I shall be right here."

She finished by sitting down in an armchair in a corner and closing her eyes.

"You heard her, this could affect our whole future!" Hermione told the others as they pored over their lists and ticked boxes.

Harry sighed. "I just want to give up Potions."

"It's like Erza said, you can't." Ron muttered gloomily. "If we could ditch our current subjects, I'd drop Defense Against the Dark Arts."

Hermione looked shocked by the very idea. "But that's very important!"

"Please." Ron snorted. "I'd rather Meledy teach me. That bumbling idiot just kinda flailed around before legging it, while she handled all of those pixies by waking up."

Harry snuck a glance at Meledy's paper and when he saw her mark Divination, he quickly checked it as well.

In the end Harry, Ron, and Meledy ended up with the same subjects, while Hermione and Wendy signed up for everything.

"Meledy! Meledy!"

The girl stirred and sat up slowly, blinking sleep from her eyes. An almost visible aura of evil intent began spreading from her as she realized that one, she wasn't asleep anymore and two, she hadn't kicked her mind in gear yet.

"What?" She asked.

"I- I don't know who did it!" Neville sounded both frantic and terrified. "I just found-"

Words failed him at that point and he dashed up to the boys' dorm, Meledy following him curiously. With one last wary look at her, Neville pushed open the dorm door. Meledy took in the sight and swore.

Her things had been strewn around everywhere. Books lay open and in some cases ripped apart, her clothes were carelessly tossed all over the room, her bed was in complete disarray, and to make things even worse, the curtains she always hid behind when she changed were in tatters.

Harry chose that moment to come in from Quidditch practice and his jaw dropped. "What on Earth happened here?"

"I don't know, but when I find out..." Meledy bent down and picked up one half of her broken wing tiara. "Someone will be in pain."

"Someone's been looking for something." Ron observed as he walked in with Dean and Seamus. "Is there anything missing?"

Meledy started gathering her things and Harry quickly dashed over to help, causing Dean and Seamus to exchange knowing looks. It wasn't until the pair tossed the rest of Lockhart's books into her trunk that Meledy figured out what was missing.

"Riddle's diary is gone." She told Harry quietly.

"What?"

Ron heard them. Nudging his head towards the stairs, he left and the other two followed him downstairs to Hermione and Wendy, where Meledy quickly told them what happened.

Hermione looked scared. "But... only a Gryffindor could have stolen... I mean, no one else knows our password-"

Harry nodded. "Exactly."

The next day had perfect weather.

"Excellent Quidditch conditions!" Wood was in a happy mood. "Harry, eat up, you'll need lots of energy."

Harry ignored him, choosing to instead join Meledy in carefully observing everyone at the Gryffindor table and trying to guess who might have stolen Riddle's diary. Eventually, however, it was time for the game and the pair left, accompanied by Ron and Hermione. Wendy split off from them, saying that she wanted a word with one of her Ravenclaw friends, but promising to make it in time for the game.

As they left the Great Hall, all thoughts of the diary fled from Harry's mind when he heard the strange voice again.

"Kill this time… let me rip… tear..."

"It's that voice again!" He cried out in mixed fear and exasperation. "I just heard it now – didn't any of you?"

Ron shook his head and Meledy shrugged, but Hermione slapped her forehead. "Harry – I think I just realized something! I have to go to the library!"

And she sprinted off.

"Wonder what she understood..." Meledy stared after her.

"Loads more than I do."

Harry sighed. "But why does she have to go to the library?"

"It's typical Granger behavior." Meledy grumbled. "When in doubt, ignore giving any explanation and run off to stick your nose in a book."

"You'd better get moving." Ron prodded Harry as people began heading for the Quidditch field. "The match is about to start."

Ten minutes later, everyone was at the field. Wood was off on a warm-up lap, Madam Hooch was preparing to release the four balls, the Hufflepuffs were having a last-minute strategy debate, and Harry was about to mount his broom when Professor McGonagall ran into the stadium, carrying a large megaphone.

"The match has been cancelled." She announced, ignoring both the booing crowd and Wood's protests. "All students are to make their way back to their house common rooms, where their Heads of Houses will give them further information. As quickly as you can, please!"

Then she lowered the megaphone and motioned Harry over.

"Potter, I think you'd better come with me." She glanced past him at Ron and Meledy, who were approaching quickly. "And perhaps you both should come along as well."

"This will be a bit of a shock." She told them as they headed towards the hospital wing. "But there has been another attack… the biggest one so far."

Harry swallowed nervously as McGonagall pushed the door open for them to enter.

Madam Pomfrey and Mira were both examining a fifth-year who Harry recognized as the Prefect they'd mistakenly asked for directions to the Slytherin dorm. Lucy was also there, staring with angered disbelief at the bed furthest away. And on the bed closest to them was Hermione, completely still and with open glassy eyes.

"They were found near the library." McGonagall explained. "I don't suppose any of you can explain this? Miss Marvell was holding it when..."

The trio fixed identical horrified gazes on the bed Lucy was focused on, completely ignoring the small mirror McGonagall was holding up.

"Well, I will escort you back to Gryffindor Tower." McGonagall sighed. "Professor Scarlet will take over from me once everyone's there."

"Wendy..." Lucy muttered as they left and she approached the immobile girl's bed. "What did this? You're tougher than any of the students here… so what happened?"

One of her eyes began flashing red and wisps of violet energy started swirling around her.

"We should leave quickly." Mira told Madam Pomfrey when she saw that, turning into Satan Soul and holding up most of the hospital wing's occupants at once. "Leave Wendy and Sir Nicholas, but get the Hufflepuff boy. This place is about to become ground zero, so we must evacuate immediately."

Stunned, Madam Pomfrey silently did as told. She barely managed to carry Justin into an emergency side room and close the door when a colossal force smashed into it. Thankfully it held.

"What's happening out there?"

"Lucy's self-proclaimed little sister was just brought in." Mira explained. "Lucy's magic gets unstable when she's over-emotional or in distress, and that's putting it lightly."

Another blast rocked the door and Madam Pomfrey quickly locked it, just in case. "How bad can it get?"

"Lucy will harm neither Wendy nor Sir Nicholas." Mira sighed. "But other than that… if we're lucky, we might be able to salvage some equipment."

Madam Pomfrey paled. A few more minutes passed…

"Something's wrong." Mira frowned. "It's over already? Hold on, I'll go check."

She carefully unlocked the door and opened it a little, peering outside.

Wendy and her bed were untouched. Most of the beds, in fact, only needed to be remade. A few smaller items were strewn about, but most of the cabinets and bigger things looked ok. Lucy was sitting in a chair next to Wendy's bed, clutching a bottle of alcohol while a house-elf set down a crate full of them next to her.

"Zappy." Mira called out to the elf. "What happened here?"

"Mistress called on Zappy to bring her alcohol." Zappy explained. "Then Mistress began drinking and calmed down. Miss should come over here and check, though. Something strange is happening to Mistress' eyes."

Mira walked over to confirm. Both of Lucy's eyes were blank, and while one was still her normal brown, the other iris was almost a quarter red. The red seemed to want to spread, but it looked like it was being held back. On top of that…

Mira looked puzzled as Lucy held up her bottle for another sip. "She doesn't even notice me. And her movements… look automatic, as if she's doing it unconsciously. What on Earth is she up to?"

"Mistress also said that she's going to a fight." Zappy added. "She ordered Zappy to force her to drink if she was unable to do it herself, and to run away if her eyes became completely red."

"Lucy..." Mira stared into Lucy's eyes trying to see some life in them, but found none. "Just what are you doing?"

"All students will return to the Gryffindor common room by six o'clock in the evening. No one is allowed to leave the dorm after that time. You will be escorted to each lesson by a staff member. No student is to use the bathroom unaccompanied by a teacher. All further Quidditch training and matches have been postponed. All evening exercises have been canceled. That is all."

Erza rolled up the long parchment and sighed. "I din't think I have to say this, but we are in a dire situation here. Unless the culprit behind those attacks is caught, Hogwarts is likely to be closed down. If anyone has any information that would help us investigate or apprehend the attacker, it would be much appreciated."

"Also, each house has been assigned two of our mages who will stand guard over the houses from six o'clock in the evening until breakfast. Myself and Gray Fullbuster will be the ones to look after you. Please do not make things difficult for us with attempts to break curfew."

With that, she sat down in her usual armchair and crossed her legs.

"Excuse me, Professor." Lee Jordan approached her. "But among the victims there has been a Ravenclaw, a Hufflepuff, three Gryffindors, and Sir Nicholas. None of the people attacked have been from Slytherin. Since the monster belonged to Slytherin and the culprit calls himself Slytherin's heir, don't you think you should force the information out of them or just throw them all out?"

"Surely you don't think the staff haven't made that connection, Mr Jordan?" Erza asked him. Without waiting for an answer she continued. "However, there is little we can do without concrete evidence. Do remember that Slytherin is the house of cunning. It's highly unlikely that if it was truly a Slytherin student behind all this, they would let us know about it."

"No." Erza shook her head. "You won't like what I'm about to say, but I believe the culprit to be a Gryffindor student."

She held up a sword to silence their protests. "Think about it. If a Gryffindor was behind this, wouldn't it make sense that most of the people affected by it are those who spend the most time around that person?"

Some of them still looked mutinous, but others lapsed into thoughtful silence.

"Ah, Gray." Erza nodded to the man who broke the tense atmosphere when he walked in. "Shut the door, will you?"

Gray nodded and slammed his hands together. A thick wall of ice spread over the dorm exit, preventing anyone from leaving unnoticed. "There, will that do?"

"Perfect."

"There." Freed lowered his rapier, studying the rune barrier for any flaws. "This will stop people from leaving after hours."

Evergreen looked around the Hufflepuff common room, where the students looked relieved. "Not that we have to worry about any of this lot sneaking around..."

Mira smiled sweetly. "I don't have to worry about people trying to sneak around after curfew, do I?"

The gathered Ravenclaws hastily shook their heads, many of them trembling in fear. Lisanna laughed.

"No, Gajeel, no eating."

"But..." Gajeel stared at the Solid Script barrier in front of the Slytherin dorm exit. "It's made of iron..."

"Fine." With a wave of her pen, Levy turned the iron into granite. "Problem solved."

"What do we do now?" Ron asked Harry and Meledy quietly. "D'you think they suspect Hagrid?"

"It's possible." Meledy sighed. "But it'd be better if we went down to him to talk. I don't believe he's behind this, but he was here when all this happened last time, so he might know something."

"Just one problem." Harry pointed to Gray's ice barrier. "That."

"Oh, I can get us past that." Meledy smirked. "Harry, grab your Cloak. You and Ron will need it."

Ten minutes later, Meledy approached the ice barrier with Harry and Ron hidden under the Invisibility Cloak and trailing behind her. "Erza-papa."

"Is it time for that important thing the ghosts wanted to tell you?" Erza checked the time. "Fine. Gray, let us out. I'll accompany Meledy both ways, so we'll come back together. You can handle things here on your own, right?"

"Sure." Gray made a gesture and part of the ice blockade vanished. "Be careful."

Harry and Ron quickly snuck out behind Meledy before Gray closed the barrier up again.

"So what exactly do the ghosts want? Any idea?" Erza asked Meledy, keeping one eye on her surroundings warily as they walked. "From what I could gather, it sounded serious."

"Dunno." Meledy scratched her cheek. "But I think they might have some clue or advice regarding what's behind all those attacks."

Ron stumbled. Erza sent a suspicious glance at where she head the noise come from, but continued walking.

"Well, if they do indeed know something, it'll be a great help." She conceded. "By the way..."

Before anyone could react, she drew her sword and threw it. It embedded itself in the stone wall, inches away from Harry and Ron.

"If you two had some urgent business outside your dorm, it would have been better to tell me."

Harry slowly pulled the Cloak off and put it away, staring with wide eyes at the quivering sword in front of his nose.

"What are you two up to?"

"W-we were going to… to visit Hagrid." Ron stammered, too shaken to think of a lie. "We think he might know something about the Ch-chamber of Secrets, since he was blamed for opening it last t-time."

"Makes sense." Erza nodded as the sword vanished. "Twenty points from Gryffindor for each of you. We have those new rules for a reason, you know. The Entrance Hall is on the way to where the ghosts are, so I will escort you there. When you're done talking to Hagrid, make him bring you back up to the dorm. Understood?"

"Yes, Professor!" The pair chorused.

Sir Patrick nodded gratefully to Erza. "Thank you for escorting Lady Meledy here. Will you accompany us, or do you have pressing matters to attend to?"

"I shall wait outside." Erza decided. 'I plan to escort her back, but at the same time I shall not intrude on something you probably intend to be for her only."

"Indeed, that is the case." Sir Patrick bowed. "Once again, thank you."

"Now then..." He turned away from the door Erza just closed and headed with Meledy to a large gathering of ghosts. "After Sir Nicholas was attacked and Petrified by the monster from the Chamber, we decided that some action needs to be taken. Unfortunately, we as ghosts are incapable of doing much more than scouting."

"I'm guessing that's where I come in."

"Yes." The Gray Lady took over. "We held a vote and it actually came out unanimous, so we're going to teach you something no human should know. We'll teach you how to destroy spirits."

"There aren't many things that can do what happened to Nicholas." The Bloody Baron added gravely. "And most of those that can are malevolent spirits or immaterial creatures. Since such beings are immune to physical attacks, we need a weapon that can affect the soul directly, and your special brand of magic can be refined into such a weapon."

"Form that glow you did on Nicholas' Death Day party." The Fat Friar instructed her. "We'll try to change it from just being able to touch to being actively able to hurt them."

Meledy did as told and several of the more well-read ghosts, including the Gray Lady, began inspecting it.

"It treats us as solid beings..." A ghost observed after trying and failing to push his hand through it. "But there's no negative feedback from it as it is now… Lady Meledy, try to force yourself to wish us harm."

"Wouldn't what she did to Sir Nicholas classify?" The Gray Lady recalled. "If this magic in its' normal state only treats ghosts as solid, Meledy's attack on that strand that held him together should have pushed Sir Nicholas away, not slice through it."

Meledy focused on the feeling of wanting to cut through Nick. The sharp blue glow around her hand flickered, before small parts of it turned an ominous crimson.

"Something's happening..." One of the scholar ghosts adjusted his glasses, then poked one of the red spots. He instantly stepped back with a yelp of pain.

"Amazing!" He looked ecstatic. "To think we'd get results so quick-"

"I'm sorry..." Meledy panted as the glow faded. "This is really hard to maintain..."

"Wait, wait, wait..." The ghost examined his finger closely. "Part of my finger is missing, which is strange… that red glow tore it out, but it should have reformed by now… unless..."

A hushed silence fell over the ghostly crowd as realisation began to set in.

"Lady Meledy..." The scientist spoke in a tremulous voice, as if afraid to voice his theory. "Did you… did you just release part of my soul?"

Next up: Creepy Crawlies. That'll be out in a little while, so look forward to it.

Thanks for reading!