At first they tried to drive him away, nobody wanted to look at a ghost that resembled their dead son, least of a family of ghost hunters. However no matter what they did, even if his own parents attacked him, he would eventually wander back into the Fenton household. He never spoke, he didn't seem to possess the ability to do so. He was just a silent form that stayed in the house watching them and trying to do normal things which was difficult in his form.
He couldn't hold a tangible form for long so usually he couldn't interact with any objects, but occasionally with what looked like great focus he was able to pick up the TV remote and turn on a show. It was disturbing, but since he refused to leave they had to get used to him haunting them. It wasn't easy, but everyone found there own way to deal with the ghost of their son, Danny's phantom.
Jazz adjusted to it the most easily, though even for her it wasn't easy. She was unnerved by the quiet ghost, she'd learned that not every ghost was entirely evil from the many ghosts that frequented Amity park, but it didn't make it easy to have one hanging around. She tried to avoid him, but inevitably he'd gravitate to her and start watching her peacefully occasionally making a movement trying to say something she couldn't quite understand. Eventually she just let him have his own way and stopped trying to hide in her own house.
She was willing to let the white haired boy sit by her side in companionable silence while she read, allowing him to look over her shoulder. Much like the living Danny he would wrinkle his nose at whatever boring subject she was reading and roll his eyes when she tried to explain its importance.
The one sided conversations weren't as awkward as one might expect and she could almost forget he wasn't a living person until he slipped through something or floated away. Still she never turned him away if he came to her and though she tried to teach him sign language he never really took to it.
Her parents were much harder to convince to come around, they couldn't accept that their son had become a ghost and did everything in their power to make him leave. When nothing worked they, much like she did, attempted to staunchly avoid him, but his natural curiosity had him following them around when they worked. Although they never said it, Jazz knew the biggest problem was that they blamed themselves for Danny's death when he turned on the Fenton Portal. It was their design that killed him all because they made a mistake and he was a bit reckless.
Her mother finally broke when the ghost of Danny started to unconsciously become fully solid for short periods of time. His hair would turned black and his ectoplasmic green eyes reverted to their original shade of baby blue. The first time it happened he was going to the kitchen and unconsciously changed with no warning. Maddie yelled to him calling his name for the first time rather than, ghost. Much to everyone's surprise he didn't fade through the door he was walking to, instead he bumped into it, but by the time he fell he looked like a ghost again and sank through the floor. Nobody was sure what to make of it, Danny's ghost most of all. He kept staring at himself and touching things, which he would inevitably fade through.
The second time he was standing near his mother while she was trying to work on an experiment. She glanced over prepared to tell him off, but he had changed while she was looking away. To the naked eye it seemed her Danny was standing right next to her, despite the scientist in her telling her it was a ghost she grabbed him and dragged him into a hug which he silently returned. She could feel his body emitting heat and it felt exactly like the last hug she had given him while he was alive only hours before the accident. It didn't last long, only a few breaths before he was standing on the other side of her once again a ghost.
After that point she made a conscious effort to try to accept him as he was, but kept in mind that she was no longer dealing with her living son. He was something entirely different, but whatever he was, he was here to stay and she was going to live with that the best she could.
Jack finally came around the first time he saw the ghost cry. He came across Danny staring at the picture of himself while he still alive they kept as a small memorial. He was reaching out to touch it when he was interrupted by Jack's voice, "Don't touch my son, you ghost." Of course Jack knew the picture wasn't his real son, but it held the memory of him and he didn't want some copycat ghost touching it.
He felt himself pause when the ghost looked at him with tears streaking his face. Jack's first thought was that he was crying about his own death. That thought struck Jack that somewhere he already knew that the ghost was truly the ghost of his son even if he didn't want to accept it. "I'm sorry," he said to the ghost of his son not entirely sure why he was apologizing or what he was apologizing for. Danny looked over and nodded summoning up a small smile before silently walking away pausing to look at the photograph one last time.
Once the entire family had silently come to the agreement that they couldn't kick the ghost of their son out they decided it was time to tell his friends. Sam and Tucker blamed themselves for letting Danny die and were never able to enter the Fenton household after that day. However despite feeling the similar guilt Maddie and Jack dealt with, their reaction to Danny's ghost was entirely different.
Instead of denying that he existed or that he was their Danny, they latched on to the belief. They wanted to force their guilt away by seeing that Danny was still around, but in some ways it had the opposite effect. Seeing his smile when they found themselves in Fenton works was thrilling, but the fact that he wasn't truly alive and couldn't really speak to them made them feel terrible that they reduced him to this state.
They tried to tell him everything that had happened in school since he had disappeared focusing on only the positive things and telling funny stories. His silent laughter and bright smiles reassured them, but the guilt never really went away. They wanted to hide from the quiet ghost who constantly reminded them of their grave mistake, but leaving him alone would be worse so they forced themselves to go back and visit him occasionally. It wasn't the same, but eventually they too grew used to it and began to accept it. The pain never truly left, but they grew to like the ghost of their friend.
A/N
OK, so that was either a short one shot of Danny's ghost returning after he died in the portal accident rather than becoming Danny Phantom or it was the first chapter of a story centered around Danny's ghost.
Please let me know what you thought, thanks for reading.