This is just a little thing based off of a headcannon I have. Later I may make an OC-based fic for this as a sequel (not to say other characters won't be included or focused on, of course).

The first sign was his hair – the tops were turning a bright, pure white and it slowly moved towards his roots. This was pointed out many times – especially as it stopped somewhere in the middle of his hair so that the other half, to the root, was still black. After even random people at school began to point it out, he just decided to ignore it.

His friends and family got worried about it, and his parents constantly asked to do tests on him, he refused. It's not really that alarming - to him at least. His white hair could just chalk up to stress, and it should go away once he relaxes a bit. He still has trouble with balancing school and fighting ghosts, even if he's gotten on better terms with a lot of his past enemies.

The second was frequent though it wasn't as alarming as the people around him would make it out to be. In short, his eyes began to glow a toxic green far more than usual. Normally, his eyes would glow when he was feeling angry but now it happened at completely random times. Sometimes his eyes would even start to fluctuate between the ghostly toxic green and his human ice blue.

He honestly didn't think too much of it, and why would he? He was used to his eyes turning a green glow and staying that way depending on his mood. He was barely surprised anymore. It took a while for the people around him to get used to it though, since they had just gotten used to seeing his green eyes when he was angry or feeling mischievous. Now, seeing it all the time made it harder to explain that he's feeling alright.

The third sign became the one that actually made him begin to worry, and understand why his friends and family were so worried as well. His ghost powers were starting to slip through once again, just like when the accident had first happened. Though, then, it was just a bit of invisibility and phasing through solid objects – or accidentally going ghost when he meant to stay human and vice versa.

This…this was far more dangerous.

He woke up one morning to find his room completely frozen over. That was pretty easy to thaw out, but every time he zoned out or found himself nodding off, he would begin to freeze the area around him. Pretty often, Sam or Tucker would wake him up during class when he would start to daydream or nod off, and his seat would begin to freeze over. One time they didn't, and he woke up to find the classroom had dropped down to below freezing – he being so icy cold it actually hurt to touch his skin, as Sam and Tucker had told him.

Another time, he had actually begun to let out his ghostly wail by accident. It was hard to explain it wasn't an accident – until he accidentally did it in the middle of yawning.

At that point, he allowed his parents to run some tests on him. But, of course, they reported that it would take a while to decipher the data they gathered. His situation was rare, and there was only one other halfa alive on Earth. That halfa, of course, is his archenemy who would give him information only if he does something for him.

So, he went to the only ghost he knew would have information for this – Clockwork.

He thought, since he and Clockwork were getting along so well, that he would get some information. Though, sadly, he couldn't. Apparently telling him would alter the timeline too much, and there was a bigger chance a bad outcome would happen. Though, before he left, Clockwork had, with obvious hesitance, told him that if he needed a place to stay in the Ghost Zone, his realm was always open.

Danny was grateful, since Clockwork was practically his closest friend in the Ghost Zone, but that did not ease his worries of what was happening to him. So, in the end, he went home to report that Clockwork also had nothing to tell him.

Though it was annoying to have his powers malfunction so much, the fourth and last indication of what was happening to him made him finally realize what was happening. Or, at least, he had a theory of what was going on.

He couldn't go ghost anymore.

By time this had happened, his eyes had completely taken a nice – in his sister's opinion – combination of the usual green and blue, glowing to the point that anyone would easily be able to find him in a dark room.

He, with the others, had come up with two theories for this. Either his ghost powers were growing and settling, so for a short amount of time, he couldn't turn to his ghost form. The other, though, was that he had probably merged with his ghost form, which would explain his new looks and why his powers had also transferred over.

So, since it wasn't positive yet, he decided to train himself to control his powers while still human. It helped him think about something else while the idea that he was now completely formed with his ghost half was slowly coming up. But that's not to say he didn't have a good time trying to control his powers – learning how to float and such while human was fun – though Tucker would never let him live it down when he had to stay silent for a month to control his ghostly wail. After all, it was annoying that every time he said something a bit too loud, angrily, or even yawned his ghostly wail would slip out and make him feel drained for the rest of the day - not to mention the damage he would cause.

His ghostly friends seemed to be as understanding as his human ones, surprisingly. It was strange as he found himself feeling an odd pull towards the Ghost Zone, and soon he was spending hours there, exploring more, talking to ghosts he was more civil with, and he slowly found himself falling in love with what he named his second home.

It was when, while chatting with Ghostwriter, that he realized how deep he was with how long he's been spending in the Ghost Zone. Well, it was when Sam, Tucker, and Jazz suddenly crashed in – pissing off the ghost who was very protective of his books – all of them completely worried and yelling over each other.

Only after a bit – more like a lot – of shenanigans including an hour long rhyming spree due to an angry ghost bookworm, a frozen room, and shouting – they finally told him that he's been missing in the Ghost Zone for nearly a week. Even though he kept arguing that he was sure he told them just a few hours ago that he was going to have a chat with Ember. True, he had gotten side tracked since then, but still! It couldn't have been that long!

Sadly, after going back to the human world he learned he was gone for that long. But it couldn't be possible, it only felt like a couple of hours to him after all!

Either way, his parents then gave him a watch to wear whenever he would go to the Ghost Zone, to beep when the time extended past how long he wanted to stay in the Ghost Zone for. Though he did use it, there were times he found himself ignoring it in favor of exploring with younger ghosts or chatting with others. He had soon lost count of how many times his parents or friends went into the ghost Zone looking for him. On quite a few of those accounts, they nearly died from some hostile ghost or other.

Still, his powers grew as he trained and he found himself feeling almost distant from his human friends and family. It wasn't until he realized they all seemed to be getting older and taller than him until it was his senior year, and he still found himself looking 15 though he felt 18.

Sam and Tucker went away to college though he stayed with his parents, not knowing where to go or if he could go anywhere. His trips to the Ghost Zone went from weeks to months, and every time he came back he felt more and more distant from his human friends and family. Soon, calling Jazz, Sam, and Tucker felt more like a chore or forced than usual. Even talking to his parents and sitting down to eat human food felt strange.

He even found himself removing him from other humans – he was far more ghost than human now though, wasn't he? It made sense, he couldn't see himself as human. Even the ghosts were seeing him more as one of them then something in-between.

But then he went in the Ghost Zone…for a very long time. Partially, he blamed the ghost wolves that had destroyed the watch. He couldn't be too sad or mad, though. He told himself he could keep track of the time before flying off with his new friends.

By time he realized – or perhaps remembered – that he should probably go back to the human world, he found the usual entrance was closed. That was odd, since no matter how long he was gone, his parents normally left it open for him. So, he had to find another portal that usually popped up near his house every 3 hours. During his stay at the Ghost Zone, he had gotten pretty good at keeping track of the naturally appearing portals and where they go, after all.

He came out to find Amity Park was completely different, from the buildings to the people. He, himself, had gotten new clothes from Ember but they were very simple – a black t-shirt and a black sweater with jeans. Though they were kind of ripped and dirty with ectoslime and other things from his adventures, he wasn't completely out of place.

He went to fly to the Fenton – his home, first. His heart – which had felt frozen for a while – had dropped as he looked, horrified, at the demolished building. Looking closer at the wreckage, he realized that it seemed to be burned down, explaining why the portal was closed. It must have burned down with the rest of the building.

Bolting from there, he looked for the next person he knew could tell him what happened. He couldn't call Sam, Tucker, or Jazz after all – he forgot their phone numbers, it's been so long.

It took a while, until nightfall, for him to find Valerie in a totally ghost-protected house. But it was wrong. She was taller - too tall, too old…

She was the one to tell him the truth.

He had lost track of time for too long. It had been 15 years since the last time he went into the ghost zone. His parents' lab had burned down in a horrible accident and they, unfortunately, had died, so everyone had thought him dead, including his friends and Jazz. Luckily, she kept in contact with them, so he learned they all had quite successful lives spread out in other states.

Jazz had begun being a therapist for kids, Tucker began his own company for tech, and Sam…she had actually gone into the ghost business – forming a small agency of her own. So far it was very successful, and she was gaining in popularity. Everyone had moved on, mourned his "death" – or perhaps barely, he did grow distant from them, after all – and gotten successful in their own right.

Him though? He had spent his time learning every inch of the ghost zone. Sure, he had claimed a few titles and became known as one of the most powerful ghosts, but that didn't really mean anything. He had no place to stay, nowhere to go. He wasn't the protector of Amity anymore. In fact, he would probably be seen as some common ghost, to be feared.

His parents were dead, his friends moved on, and even he had changed – despite being in denial. He had learned things from the Ghost Zone, and though he physically looked 15 and still acted the same way in some regards, he had still grown.

Declining Valerie's offer to stay over, he wandered Amity for a while, avoiding public eye, trying to soak everything in. He wasn't Danny Fenton anymore, Danny Fenton didn't exist. If he was being truthful, Danny Fenton began to disappear the day of the accident, when he had first became a ghost.

With no place in the human world anymore, he, regretfully, flew to a nearby portal that had appeared.

It was then he began to live out the rest of his days as a ghost. No longer Fenton, but now he was officially, and forever, Phantom.