In terms of the Guardians, Manny decided, things weren't bad, but they could be better.
It didn't go unnoticed by the Moon, that as they gained more believers, the Guardians had less time for children. Of course, what they were doing in their own realms was extremely important, so he couldn't exactly pull them from their duties as they were. He thought that, perhaps, it was time for a new spirit to shoulder the responsibilities that they could not.
It was just as important to the Moon that a new Guardian was able to teach children the joy in things outside of playtime. There was much to gain from reading a book, or from music or painting and other such academics. Someone new would have to be able to be versatile in the ways that the current Guardians were incapable. With his requirements set, so began his search.
The Moon watched many people. He searched through the highest towers, and the most decorated houses. He sought out the bravest warriors and the wisest elderly. Most of the people he sought out had potential. None of them felt right, exactly.
Until one Jackson Overland.
He wasn't too out of the ordinary, but he had an at least average affinity for most trades and almost equal enjoyment of all. He was personable and he did well with kids. He had a charisma that endeared himself to the Moon. Not enough for the Moon to choose him for Guardianship right out of the gate, but enough for him to keep an eye out. What really forced the Moon to make a move, and tipped the scales in Jack's favor (Or perhaps against it, depending on who you asked) was one fateful morning on some very thin ice. Worried that he might have just lost his best candidate, Manny rose Jack the next night.
He figured that as Jack grew as a spirit, it would become more and more obvious how fit he was for the Big Four.
One thing to know about Jackson Overland is that he hadn't had much time in life to learn. At least, not from a book. What was most important was being able to care for his family, what with his mother being so frequently ill, and with his father being off to who-knows-where so often. Every problem, be it academic or otherwise, he dealt with in good humor. He knew what he needed to know; writing, reading, basic math. He had a keen mind and kept up well enough for the amount of time he spent schooling. Had things been different for him, he might have made a good scholar.
Most of that carried over into his next life.
Jack Frost was lonely. This was well known. By the Moon, and by Jack. He could go years between finding other spirits, and of course, there wasn't a person who could see him. Though Jack found a lot of joy in making Snow Days even alone, getting walked through got tiring.
So, it was normal for Jack to take breaks from snowmaking in favor of other things. After all, there's a lot more to fun than snowball fights, and running around outside on a snowy day. Sometimes, fun is being able to sit inside with a good book or a pencil and a piece of paper. Often, he found himself in a library. Reading was a fond pastime of his. Mostly, he dabbled in fiction, though as he took interest in other subjects, he found that he preferred subjects like philosophy and literature quite a bit. Around the turn of the 19th century, he took a larger interest in the sciences.
There was also a simple joy in being able to coexist in a room full of other people. Unlike during more active pastimes, there wasn't as much of a risk of being walked through. Fiction was a rewarding escape from his reality. He could pretend that he was someone other than who he was, and though he wasn't as able in the physical world, he was able to have a good conversation with words on paper and the people in his imagination.
It was quite nice for him to bask in the companionable silence of other people in a library. He often pretended that some of it was also meant for him. It held him over well enough until he was able to share some real companionship with real people.
And maybe, outside of that, he would offer some help inside the library. He'd lead a child to a storybook they'd been missing, or he would help some poor student solve their equations by slipping them the right textbook. Sometimes he would do some good by solving some problems for them while they were distracted. If he was feeling extra generous, with a bit of magic and a crumpled piece of paper (in lieu of a snowball) he could bring some fun to someone who needed it.
Maybe the Moon took notice, and that was why he'd eventually gotten the call to help form the Guardians. But after his first struggle against Pitch black and his Nightmares with the other Guardians, a lot of his skills translated well in helping out his new believers.
As they grew, he was able to help Jamie with his math, and Monty with literature. During their senior year, Jack encouraged Pippa to pursue her interests in science. She went on to become an accomplished Biologist. Monty did well as an artist to no-one's surprise and, perhaps taking a lot after Jack himself, Jamie became an accomplished children's book author. He went on to help many more kids as his believer-base grew.
For Jack, maybe things weren't perfect, but they were better.