Disclaimer: Still don't own it… Too bad. If I owned them, there would be more Danny Phantom and Luna would still be alive, as well as Fred, Tonks, Sirius, and many others.
The swirling Green and Purple landscape of the Ghost Zone was different than the blue skys of Amity Park, to say the least.
Danny searched the Ghost Zone for days to see if Sam would come back as the ghostly girl she had when possessed by Undergrowth, but if she was, he couldn't find her. Danny didn't know what to do. He had ended Skulker, and had no sense of direction in his afterlife. He decided to rebuild ectoweapons, including the Fenton Thermos and Bazooka. Still finding no enjoyment, Danny realized he had no more purpose.
"Why not train?" Danny mastered duplication. He could utilize up to 10 duplicates without tiring, but eventually that got boring. Danny also created a parallel pocket dimension to keep stuff in, like a portable storage locker. Danny gained powers of telekinesis, weak telepathy, and, of course, the Big Bang, as he called exploding into different forms of ectoplasm. Selective visibility was also new. Appearing to those you want to appear to, but not others.
Danny decided to wander. He was more than able to protect himself, and he needed something new in his afterlife. He eventually found a portal that, albite red in color, seemed to send him to Earth.
Danny drifted from town to town, aimlessly wandering. There seemed to be few portals, but one ghost, however, found it's way to his new world: the Box Ghost.
Boxy decided to lead him on a world-wide journey before getting shot by a Fenton Bazooka Danny rebuilt and was teleported back to the ghost Zone. By this point, Danny had reached England.
As the sun drifted into the sky, Danny spied a small, ordinary suburban neighborhood with a milkman coming down the street. Glancing a few houses ahead of the man, he saw a basket on the doorstep of a certain house, one number 4 Privet Drive, Little Whinging, Surrey. Swooping down, he saw a roughly one-year-old baby sleeping in the basket. In one hand, it held a letter, and the other clutched its blanket. The child had a shock of raven-black hair, and, lifting the blanket a bit, Danny noticed the child was a boy. Giving him a once-over, Danny solemnly noticed that the babe looked similar to his human body, albeit several years younger.
Smiling down at the child, Danny decided to watch the boy, for the time being at least. Not like he had anything better to do.
As the milkman finally arrived at the tragically ordinary house, he set down the ordered milk crate next to the basket. The clinking of bottles, however, seemed to wake the baby. The child cried out suddenly, shocking the man and making him fall flat on his rear, surprise etched across his face.
"Don't know what whoever put 'im 'ere was thinkin', but th' poor child will find no friendly faces 'ere," the man muttered, before ringing the doorbell a few times. Sighing with pity, the man walked back to his truck and drove off to continue his rounds.
Petunia Dursley knew the milkman had never had any inclination to ring the bell for a chat before, and she was quite pleased with this arrangement. Whatever had possessed the man to do so this particular day was beyond the woman who bore strong resemblance to a horse, and as she opened the door with foul profanity on her lips and every intention to slam the door, she was quite suddenly startled at the basket on the step, and the profanities died on her lips. Sitting there, out in the open, was a crying baby in a basket with a letter clutched in it's grubby little hand! Worse yet, it's black hair looked like James Potter's, and his vivid green eyes were exactly like her freak sister's.
Stifling a shriek of indignation, her mouth twisted, fell open, and she let out a few staccato yelps. Running into the house, she slammed the door.
Bored, Danny became selectively visible to the baby and petted his hair, caressing his chubby face until he calmed down. By this point, the door opened a crack, and Mrs. Dursley peeked out of the door with large, frightened eyes and a large black frying pan.
Danny's eyes popped wide open. She wouldn't kill the child, would she? Danny honestly had no clue, he didn't know who these people were.
Glancing around to make sure that no neighbors would see, the odd woman used the frying ban to scoot the basket in the door. As it hit the bottom edge of the frame, the child laughed, and Petunia let out another little shriek. Hurredly pulling him in, she slapped the baby across the face. Not hard, mind you, but it was child abuse none the less.
Danny had entered the swiftly closing door and gaped. The baby sat still for a moment, shocked, and then started wailing loudly. They were pitiful wails of agony, betrayal, and mistrust.
In the door to the kitchen, Danny thought he saw his Dad reborn, but an even fatter than his muscular, but chubby, father, march through the kitchen door. "What is the meaning of this!?" The walrus-man roared, his doughy face turning red with anger. "I just put Dudders to bed and now this infernal wailing?" His face was turning an ugly, bruise-like shade which did not look flattering to the bloated whale of a man.
"I-I-I just f-found 'im o-outs-side an 'e won' s-stop wailing!
Danny sighed. These two buffoons had no idea what to do with the child, so he would stay in the shadows to take care of him. This small baby bore remarkable resemblance to himself, and he couldn't let him get hurt. What he felt was primal instinct, and he knew that this baby would be his responsibility, and maybe his new obsession.