This takes place without all that Pitch nonsense. And just so you know, I haven't seen the movie, so if any of this is horribly incorrect I'll change it after I do.

Jack wasn't a real Guardian, because North, Sandy, Tooth and Bunnymund never never hurt humans, let alone killed them.

Every time a human died, they had looked at him. Stared at him, with their glassy, accusing eyes. As the hypothermia finally overtook them, or if they had been trapped under a frozen lake, or just died of the common cold and a weak immune system, Jack knew it was his doing.

It hurt like hell.

He'd witnessed more deaths of his own fault then he cared to remember, but at the same time, he knew he couldn't ever forget any of them.

It was because they looked at him. They were facing Death.

Sometimes, he really hated himself for existing. He doubted he would - exist, that is- for much longer, because if the day came when even the great Guardians forgot about him, he would evanesce, fade from existence until all that remained was a fictional character in a few classic children's books.

"Snow is an inconvenience."

He'd heard the Guardians say it behind his back all the time, how it messed with flying and how they wished Jack would just stop with all the troublemaking.

Snow was the only thing he had that was at least partially appreciated. It was something nice to look at.

It was the only thing Jack really prided himself in.

He almost approached them, told them, "Well, I like the snow," in an effort to give a boost to his cocky, carefree reputation, but he knew that everyone else thought the same of it.

Though he would never admit it, it was killing him.

The storms he created gave the humans a reason to stay indoors.

The children that ventured outside and braved the elements were always called back in a few hours later.

In all honestly, he did it for attention. Stuck forever as an adolescent, he needed to be recognized. But nobody believed in Jack Frost. Nobody ever had. He was a verse in a catchy holiday tune or two, and nothing more.

Kids always talked about their dreams from the Sandman, and what Santa brought the for Christmas, how the Tooth Fairy had left them twice as much money for a molar, and how the Easter Bunny was really tricky with the eggs.

He'd tried to get attention from children, but they always got too cold from his presence and went to find shelter.

Then again, he did throw balls of ice at their faces...

But he'd seen how the children reacted to the real Guardians. They'd squeal with joy and rush outside in an attempt to catch a better glimpse of the legendary.

He wanted to be loved like that. He had never asked for this life of solitude.

They say you can't miss what you've never had, but when it's constantly being rubbed in his face, Jack can't help but reach for the attention.

The Blizzard of '68 was one of the craziest things he dared try. Bunnymund had hated him anyways, and he thought a snowstorm could push him over the edge, get him angry for a while.

It would have worked, if the Guardian wasn't so busy. He got an angry letter and a few glares, but the resentment faded enough over the years for the event to become insignificant.

Jack Frost was alone for eternity, there wasn't any sugarcoating it.