BLANKET DISCLAIMER; I OWN NOTHING
Jack Skellington looked at his beloved and wife Sally Skellington as they waited for the Doctor to place his final touch on the body of the child that they found on the side of the road earlier that night of Halloween. Sally and he have been married for close to three years now and were both wishing to have children. Alas the dead cannot have children the normal way that mortals do but they can ask for the creation of one from Doctor Finkelstein or adopt a dead child fresh from their burial ground and then have the good doctor reanimate them.
With this thought in mind they had went searching through the mortal realm whenever Jack was free of duties, something that the citizen of Halloween Town have been giving him more and more by taking over as much job off his overflowing desk as possible to help him and Sally have more time to 'make' children. Fleeting from graveyards to graveyards, they had come across a road accident near a dark highway empty of other vehicles that mortal so fond of. Being Halloween, Jack has the easiest time to travel using his power and had went about doing his job while searching through his usual haunts for possible child that attracts Sally's internal maternal instinct. So far, they had found none.
So when they came across the burning vehicle, Jack had wanted to just pass it by for matters of the human world have nothing to do with him, only holidays and celebrations. But Sally wanted to make sure that no one needs their help so Jack had offered to look through the vehicle, knowing with what Sally was made of she might get burned while he, other than the suits on his back, has no flesh to offer to the raging fire.
He had found a large whale of a man crushed in the driver seat and already halfway over cooked. Then he noted that the back seat's door was open and there were blood leading away from the car and into the forest. Cautiously he treaded into the forest, wishing whatever it was have died so he does not need to deal with hysterical human. The dead were far more polite and calmer when confronted by the likes of his kind.
Jack does, after all, a strong relation and resemblance to Death…
Imagine his surprise to find a small boy whose mangled neck still stubbornly connected to his body and gasping for air. The poor child was dying and his head almost come off of his almost severed neck, but for some strange reason the child refused to give up on living. Sally had followed him then, away from the danger of fire, and she had immediately taken a liking to the boy. Knowing that he will die without aid, Sally asked Jack to take the child with them to Halloween Town. Should the child survive, maybe they could ask one of the vampires or the werewolves to turn the child. But when they arrive to town, the child was dying of blood loss.
Thus it took them to their current situation. It was almost twelve midnight and the Doctor that created Sally has worked all evening to reanimate the child. He had cut clean off the head, killing the boy instantly before working to sew his mangled body back together. But since the cut was unclean, half looking as though something had chewed its way through the neck and the other half being axed off, he decided that the boy will have to live with his head able to come off, thus making him similar to the headless horseman only that he still have his head and haven't lost it…yet…
The bell tolled midnight when the child opened his new eyes. His upper face had been crushed by something and the Doctor had sewn new eyes that he had experimented with. Now the boy looked like a mix of Sally and Jack. He looked around confusedly, unaware that his body was on a different table. Doctor Finkelstein grinned and cooed, "Why, hello there, pretty baby…"