Hello dear readers and welcome to my first ever crossover! (and fan fiction for that matter). Before you begin reading I just want to make some plot things clear. I'll be using the Harry Potter books mainly, not the movies. That includes the years they are set in. [1991/1992]

I tried not to copy J.K.'s book word for word, but sometimes I couldn't avoid some dialogue. After all this story is a time travel story. However, I have attempted to re-write them in my style when I can.

Now, with that all said; Enjoy! And of course, Disclaimer: I sadly don't own Harry Potter or Danny Phantom, but any OC characters are mine.

Chapter 1: Mission Through Time

This cannot be happening...

Clockwork once more watched the images of time play out within his viewing mirror. Only moments before he had been observing time like always. Then, it happened; a key moment in time altered against his will. The Time Master frowned, hand hovering over the mirror as it replayed.

What was going on? Time had been fine only mere seconds ago and yet now it was unraveling before his very eyes. Curious, he gripped his staff tighter. Letting his power flow through. With a tap, he changed the mirror's surface into the future to see how bad the damage was.

No, "damage" was an understatement. Time was morphing; evolving into something different. It didn't take long to find the source. Watched this moment countless times before. He had watched the destined boy approach his fate. Watched their battle. Light overcoming the dark. The correct course of the future.

Instead, the hero now lay cold and dead.

In his long existence, Clockwork had never caught a change quite like this- at least seen a change he himself had not accidentally caused. But seeing how deliberate this was one clear thing appeared; something was altering the timeline.

But it wasn't possible!

Of course, there were moments when the foolish had tried to change their pasts. But this was on another scale entirely. Moving further down he watched as the world was destroyed bit by bit. The death of the boy would demolish all order and harmony his victory made, leaving in its wake anguish for all. It was like Clockwork was watching Phantom's destructive future all over again. Death, despair, and a world without hope were being shaped back into reality. If this continues, it is inevitable.

He had to do something, go against his vows, and try. Closing his eyes Clockwork paused the mirror, shifting into his elder form. Concentrating he tried with all his might to correct the timeline directly. Purple energy swirled around his body. The mirror trembled, rippling at the power. At first, it seemed it was working. But whatever was responsible had caused more damage than he'd first thought. With a static-like flicker the image shifted back to the dead boy, the Dark Lord gleefully holding up the stone in triumph.

With a rare burst of anger Clockwork growled, slamming his staff into the floor. The mirror faded back to its glossy pearl surface, reflecting the Time Master's worry back. He sighed and calmed his mind. Anger wouldn't help here. What he needed was a plan. Quickly.

Gliding to the window he gazed out into the vast Ghost Zone, deep in thought. How ironic all his hard work done for Phantom was now pointless. When he looked into this new future he saw what would become of Danny Phantom. If that wizard rose to power too soon, it would cause the death of all he loved, as well as Fenton not even getting the chance to exist in the first place.

But how to fix this? He couldn't here. Nor dare risk fixing the timeline in person. The Observants would never allow him to. At the thought of those annoying idiots Clockwork groaned, changing into his child form. How could he have forgotten those Observants? Once they got sight of the change all hell would break loose with their laws. Instead of fixing the issue they would only make it worse. No, what he needed was a repair that would cost as little damage to time.

Phantom. He frowned at the thought. Should he involve the young half ghost? It was too uncertain… and yet he could think of no one better. The teen now understood how one little thing could corrupt time, knowledge that would help him fix it without tearing it apart. But he was also young, naive and not to mention dangerous. Instead of saving everyone from doom, he might end up causing more damage. Drifting back to the mirror he summoned the images again, checking the outcome if he sent the half ghost into the past.

Clockwork frowned at the result. It was a risky plan. So many changes would happen if he went back. So many chances he would fail and destroy a lot of other timelines as well as his own. But there was also a tiny possibility he could win. And in seeing this Clockwork knew he had to take the gamble.

Realizing he needed to move fast for his plan to work, Clockwork grabbed one of his medallions and teleported out of his lair and into Casper High. In half a second he hovered above the class. A blur no one, not even the teacher saw. Even Phantom with his sharp ghost sense couldn't react fast enough to notice.

"TIME OUT!"

With his words, the world froze.

Looking down at the medallion in his hand he oddly was filled with panic. Once those Observants sensed he'd left his tower they would be on his heels sniffing out what was wrong. Even if he explained it to them they would never understand his plan to use Phantom to repair time. After all, in their eye the half ghost was a threat. Using him would sound outrageous since he'd helped create a being that existed outside of time.

Pushing his feelings away he drifted over the children to the back of the room, stopping in front of the one he sought. Amity Park's ghostly protector had a look of boredom, gazing out the window lost in his thoughts. For a moment Clockwork merely stared at him, noting the heavy shadows under his eyes. The teen had always looked tired, but after meeting his evil self a different kind of tiredness had settled there. Content as he was to have saved Phantom's future he knew he wouldn't be the same after that fight. At least, not for now.

Observing the room he noticed the person behind Phantom. Tucker Foley was leaning forward, a cheeky grin planted on his face as he was about to make his best friend's day worse. Clockwork had already seen what would happen. Phantom would cry out in shock at the poke, too lost in his mind to realize it wasn't a ghost attack. He would be told off for disturbing the class, laughed at by his peers, and given detention for his sarcastic response. Samantha Manson would be angry at Foley and the trio would be troubled for the rest of the day. The natural order of time.

But he was about to change that forever.

With a sigh he reached down and looped the medallion around Phantom's neck, waiting for it to take effect. At first, he didn't seem to notice time starting again. He huffed his hair out of his face, continuing to stare out the window.

Abruptly he frowned as he realised Mr Lancer was no longer ranting. Lazily he glanced over to the front- only to come face to face with the Time ghost. With a yelp Danny jerked out of his seat as his ghost sense exploded from his mouth, it finally catching up. He tilted back, landing on the ground with a heavy thud. Clockwork chuckled as the teen tried to untangle himself from the chair, staring up at the purple-robed ghost with disbelief.

"Clock-Clockwork!?"

The Time Master tilted his head in amusement. "It's been a while, Danny Phantom."

Danny meanwhile could only stare in shock. He couldn't believe the Time ghost was seriously in front of him; as well as pushing down the fear creeping into his chest. Slowly he got up, propping the chair back in place as he went. Nervously he smiled.

"Four days to you is a while then?"

"For me, everything is a while."

"Right…" Scratching the back of his neck Danny sat back down, finally noticing everyone in the classroom was unmoving. Quickly he looked down to see the time medallion hanging from his neck. "So, you've saved me from Maths. I would say thank you but- wait, what's Tucker doing?" He had turned right around, only to come face to face with Tucker's pointing finger.

"I believe he is about to poke you in the back."

Danny scowled at his best friend. "Seriously?"

While the teen muttered about payback, Clockwork shifted back and forth through his forms, toying with his staff. Time was short. And now he was facing Phantom, he was quickly having doubts about whether this was the best course of action.

"Tucker's not about to cause a catastrophic event, is he? That would explain why you're…here…"

He suddenly noticed Clockwork's transformation, a grim look settled on his pale face. A sense of dread filled Danny. "You didn't just come to chat, did you? Something has happened again?"

The ghost sighed, shifting quickly to his younger form. "You are right Phantom, something has indeed happened."

Danny slouched low in his seat. "Okay…What then?"

Clockwork paused, thinking of his next words carefully. " I am here because something which has happened in the past is now affecting the future. I am here because the timeline has started to change."

Eyes widening Danny jumped out of his seat, slamming his hands on the desk. " Wait a minute! Are you saying the timeline has changed in like a bad way? Like evil-self-destroying-the-world bad?"

"More like a key moment in time has been altered, and due to that change, the whole world is slipping into chaos. Your future included."

"Then you mean… My evil self has broken out and…and-" Danny struggled to think about his future self returning. He'd only been able to defeat him from sheer luck. Who knows if he could stop him a second time? He felt his pulse quicken, breath hitching in his throat at the idea of his nightmares coming true. But when he looked at Clockwork he was amazed to find the ghost quite composed.

"No. This has nothing to do with that version of yourself. Your future in that regard is safe."

The tension melted off the teen's shoulders. He sighed deeply, a weak smile appearing on his face as he slumped back down. Relief Clockwork did not share.

"In reality, this is much worse. Someone has gone back in time and reformed the past."

"What? I thought you're the only ghost that can control time?"

Clockwork looked down at his chest, watching the pendulum tick back and forth. " At directly viewing the timeline I am." He gestured to the classroom. "No other being in existence can control time as I can. But some humans can travel back if only a little." Clockwork morphed into his adult form and with a smirk pointed to the medallion around Danny's neck. " There are more of my medallions in the world than you think. My earlier creations started much weaker than the one you're wearing. So I don't worry too much about them."

Surprised Danny studied the heavy medallion closer, hearing the faint ticking ringing from the metal. " But Clockwork, isn't that still- I don't know… kind of dangerous people are running around who can time travel?"

"Only a few have them in their possession. Besides," The ghost shrugged, lazily looking out the window. "They know the cost if they alter time. It's their own responsibility if they wreck their time, not mine."

"Oh…" Danny said awkwardly, letting the medallion fall from his hand. Clockwork continued to stare outside, lost in his thoughts for a moment.

"But this is greater time travel than my medallions can. Something has physically gone back throughout time to change a key event. It shouldn't be possible to travel that far without destroying oneself, yet…it has. Thankfully time has not begun to change yet, but soon all of the time will adjust. And the world will be nothing more than a wasteland."

Danny paled. " I don't like where this is going-"

The ghost watched as the teen hunched lower in his seat, chin almost touching the surface of the desk.

"Or why you're telling me all this."

With a sigh, Clockwork began to explain his plan. " I need your help Phantom, because like it or not this change will affect you too. See, if we cannot fix this at its source and the effects of the shift take place, you will no longer exist."

"Huh?" Danny blinked. What did he mean he wouldn't exist?

The ghost closed his eyes, he needed to tell the teen what was about to happen without panicking him. If he panics there is a chance Phantom would refuse to help. But before Clockwork could speak Danny seemed to come up with his conclusion.

"Oh! Do you mean I won't be a half ghost anymore? I admit it will suck. But being normal again would be nice. I can finally get some solid sleep without worrying that the Box Ghost is going to show up and yell "Beware" in my face-"

"Danny," Clockwork said gently, tilting his staff towards him. " You would not be born."

Danny frowned. Though he had his rising fears, he struggled to follow. Was that even possible? He still didn't understand everything about this timeline stuff. All he knew was messing with time was extremely dangerous.

"Don't tell me Plasmius has found a way to time travel and changed the future to marry my Mom or something?" He chuckled weakly, hoping that was the worst of it. But sadly Clockwork shook his head.

"No Phantom, Plasmius has nothing to do with this time change. If it was that simple I wouldn't be asking for your help."

Danny felt his heart jump into his mouth. He didn't understand how he could suddenly not exist. Or more like he thought he knew; he just didn't want to say it out loud. He wanted Clockwork to confirm his fear.

"How," He muttered, catching the ghost off-guard. " How come I won't be born in this new timeline?"

Clockwork closed his eyes, picturing the visions in his mind. " There is much…much you must understand to answer you. But I don't have time to explain it all. Simply, a war will break out due to evil forces like no other. Powerful users of magic will spread across the world, capturing it bit by bit. They start in Europe. Then a year before your birth they will turn their sights onto America. Your parents are involved in the conflict and will be killed in the crossfire."

Danny gulped as his mouth went dry. So both his parents would end up dead. But then he realized Clockwork had only mentioned his parents.

"Jazz! What happens to Jazz!?"

The ghost twirled his staff, aware time was slipping away. " She will be only one year old at the time of your parents' deaths. I assume you can figure out the rest."

If Danny had been concerned about his family before, it was unbearable now. His sister would be alone, with no one. Pure fury raged through his body, eyes flashing neon green. No way was he losing his family again! Not after everything he'd done to save them. He stood trembling, not in fear but in determination. There was no question about what he had to do.

"Okay, Clockwork. I'm guessing you've got a plan to save the future. So tell me what you want me to do."

He couldn't help but smile. Even though the situation was dire, he couldn't help feeling proud of Phantom's selflessness. His own life was in peril and yet his only thoughts were saving the ones he loved. That was the thing the Observants could never see about the young half ghost. The reason Clockwork had rewarded him his second chance.

Shifting his staff to his opposite hand Clockwork held the other towards the teen. "Quickly; we have much to do and very little time to do it."

Danny nodded and took the ghost's outstretched hand. "Going ghost!" He smirked and with a surge of blinding white light rings wrapped around his body. As they broke apart black hair turned snow white as Danny became Phantom.

Clockwork laughed despite himself and swiftly teleported them to his lair in an instant. Danny shuddered as a gust of mist escaped his lungs, his ghostly body startled at the atmosphere change. Once the Time Master was sure they were alone he took the medallion from his neck, quickly flying to his mirror. He was hoping the Observants had not yet caught on to his intentions. If they did, they most certainly would act fast to stop him.

Danny shivered again at the chill rushing through his chest, gazing around the Clocktower lair in awe. It was still as freaky as he had first thought, what with the constant ticking and whirling. With a shake of his head he drifted over to Clockwork, watching him summon a blur of images.

"So…What is it that I have to do?"

The Time Master stopped and turned to him, a curious look etched on his old face. Though he already knew the teen's answer. "What do you know of Witches and Wizards?"

Danny snorted with laughter. "That they have pointy noses, warts and fly around on broomsticks with black cats? Not much."

Clockwork couldn't help but smirk. " In other words you do not believe they exist."

"Pretty much…Wait, you're saying Witches and Wizards actually exist? So that magic force you talked about is a bunch of witches going all out and turning people into toads."

"Not quite. But yes Phantom, they do exist. They are a type of human connected to the flow of magic."

"Magic…" The teen frowned, looking at the now young ghost. "So there are other people who have supernatural powers like me?"

Clockwork turned to him, a strange look plastered on his face. "Not just humans. There are entire species of creatures and abilities who exist around the world." He smirked. "Did you think we ghosts were the only beings of legend to exist? There are countless others, Phantom, all hiding around us. In both the living realm and the ghost zone. Even in realms beyond that."

He raised his time staff, making images swirl on the glassy surface of the mirror. Placing a hand on Danny's shoulder he moved them closer, words almost in a whisper like it was all some very important secret.

"Those born with magic in their veins; or Witches and Wizards as they like to call themselves, are born all over the world from every race. Some are born from the blood. But many now are born without magical parents. They live in their little world; like us, parallel to the humans without the magic gift.

"Over centuries of practice and caution, their kind has been able to hide from the world, much like us ghosts did before your parents made the portal and allowed free travel. Though the magical world has known of mine… our kind for quite some time, as many of us like to journey whenever we can into theirs."

"So, you're saying," Danny breathed, " right now there's a whole race of magical people living under everyone's noses?"

Clockwork nodded.

The teen's brow furrowed. "But- but that can't be right! Wouldn't people be a little suspicious of them? I mean magic can't be that easy to hide."

"Phantom; they are ready for those situations. Memory wiping, changing events to look like illusions or weather disasters and even public and political corruption. They have thought of it all and thanks to that have remained hidden. Well, mostly hidden."

At first, Danny didn't understand what he meant, and Clockwork tapped the mirror. An image of a woman struggling as she was tied to a post appeared, people surrounded her with touches as they edged closer.

"Witch burning…" he whispered and the Time Master nodded.

"One fatal error of a foolish woman caused years of prejudice for their kind. Unpreventable."

"Then…if we don't stop time from changing, then the world will be taken over by these magic people-"

"-No." Clockwork cut in quickly. "The magical world will be in just as much war as the humans will be. Brother will turn against brother."

He gestured to the mirror again, Danny saw a group of masked people. In front of them was an ashen man, eyes rimmed in shadows. "In the past; years before the time change there was a monstrous wizard, a necromancer. This man slowly began tearing the magical world apart, so much so even the Ghost Zone began to notice the changes. Terror and death reigned in this time, all for the sake of this wizard's greed. But…all was as it should be."

Clockwork closed his eyes in thought briefly before continuing. "This wizard kept killing, again and again till he no longer could be called human, till his humanity was washed away and all that was left of him was a vile monster. However, in rage at learning of a prophecy which would destroy him, he went to kill the baby who would turn into his slayer."

"He went to kill a baby?"

"Yes, but he undervalued the powers of the baby's mother. For she was a strong witch who had a power the wizard could never truly understand. She shielded her child and the killing magic rebounded back. Yet he did not die. He became neither living nor dead, but a mere shadow, a Shade weakened but hell-bent on revenge."

Clockwork turned and gripped both of Danny's shoulders, hoping he would realize the importance of his tale. "Phantom; this Shade then weakened, possessed a human years later to find a way to revive itself. Only for it to be stopped by the very child he tried to kill all those years ago."

"That's the incident, isn't it?" Danny stated. "The event that destroys time." He paled as much as his ghost form could. "So… that's what we need to do? Stop this shade from killing this boy?"

"You Phantom, need to stop it."

The ghost pointed his staff yet again to the viewing mirror, a picture of a dark room appearing. "I am going to send you back in time. Back to the year 1991, to stop the death of said boy. I have viewed countless ways and possibilities and this is by far the safest one I can see. I wish…there was an easier way. But I cannot tangibly affect the time stream. So you Phantom will do it for me. You will become my catalyst."

"Wait! You're sending me back to 1991!? That's like-" Danny quickly ran over the years in his head. "-Twenty years in the past!? There will be no one there I'll know, I'll be-"

He froze, understanding dawning on him. "Alone."

"Phantom." Clockwork sighed in reply to his rising panic. "True, you will be alone. But you do not have to do this alone. Others at the school can aid you in your task."

"It's just…School?" Astonished he glared up at Clockwork, floating away from him. "You pulled me out of class just to send me back in time to go to another school?"

The Time Master laughed at his childish response. "It is a school for Witches and Wizards and as fate chooses it, the place the shade will come to kill the boy."

"I don't care if it's a school for ghosts; it's still a school!"

"You don't have to take classes, you're not a pupil there."

Danny huffed muttering under his breath. "It's still a school…" Clockwork ignored the troubled teen and looked back at the mirror.

"It might pain you to be there, but out of all the ghosts I know you are perfect for this task."

"Yeah? Is it because I'm just such a nice person?"

"No, it's because of your human advantage."

Danny gave him a puzzled look. Clockwork decided to wait, hoping the boy would figure it out on his own.

"Advantage?" The teen suddenly groaned, slapping his forehead. "Of course! Because I can still use my ghost powers when I'm normal, I can hide in plain sight and still use my powers."

"Exactly. You don't need to hide in the shadows as your human form will protect your powers from any detection. At least to those not expecting it. Since you are young, no one will think otherwise at seeing a teenager running around the school."

"Perfect..."

Clockwork watched in amusement as Danny huffed angrily about. But even though the Time Master knew he could blend in easily at the magic school, he knew there would be people who would find out about his abilities. The timeline was going to change into something new no matter what he did. So the Clockwork thought it best to prepare Phantom for the worst.

"A word of warning; be watchful to whom you reveal yourself. Once I send you back I cannot help you directly. Who you decide to grace with the knowledge of your powers is up to you, but be careful who. Some might not take kindly to your…uniqueness."

"You mean there are people who would love to dissect me there as well? Great."

"Phantom, I don't think you understand the gravity of your powers-"

"CLOCKWORK! HOW DARE YOU!"

Both froze as a booming voice echoed around the lair. Clockwork hissed, his eyes flashing red and for a rare moment his anger emerged.

"Blasted Observants! They are not as naïve as I take them for!" He grabbed Danny's hazmat suit and gently tugged him towards the mirror.

"Now go."

"But what about you?" Danny hesitated in front of the portal. He didn't want to see the Time ghost get hurt because of him, not after everything he'd done.

But Clockwork only smirked in reply. "I will be fine. They cannot hurt me, but they can hurt you."

Danny went to pull himself through the portal, yet he didn't feel the ghost's grip loosen. Puzzled he looked back to see Clockwork scowling at the mirror; a strange, almost pained look on his face. It was weird to the teen; Clockwork always appeared to hold a level of composure. No matter how dire things got nothing seemed to ever faze him.

"One more thing. I believe whoever changed the timeline will be there with you. I do not know who they are, whether human, ghost, or...something else. But know they will likely try to stop you. So Danny…" Clockwork pulled him closer, almost whispering his next words. "Do not get yourself fully dead; it would be hard even for me to correct that."

The teen felt himself shiver at those words. Something about them told him the one who was responsible wasn't a pushover. They meant business. And if Clockwork, the most powerful ghost Danny had ever encountered was nervous; then what chance in hell did he have?

Still, he nodded; trying to hide the sick feeling that had settled in his stomach. The old ghost only gave him a weak smile in return. However, just as the Time Master was about to tell him something else Danny quickly caught sight of the Observants behind Clockwork, flying madly towards them.

"STOP RIGHT THERE CLOCKWORK! HOW DARE YOU DISRUPT THE TIMELINE AGAIN! YOU–"

But Danny never heard the rest. Clockwork pushed him into the mirror and closed it immediately, leaving him alone.

AN: Just a quick note: if there are any grammar errors please let me know. I'm still learning creative writing and I am curious about opinions on how I write. Any feedback would be helpful.