300 years ago, Jack was a normal human, who lived in the town of Burgess with his family. One day, he went ice skating with his little sister, but they ended up on some thin ice. To make sure she stayed calm and got out safe, Jack acted like it was just a game and made his way over to his hooked staff, which he hooked her with and threw her to safety. But at that moment, Jack fell through the ice and drowned. However, the Man in the Moon witnessed his sacrifice, and transformed him into a winter spirit with no memories of his past. At first, Jack was thrilled by his abilities, but he soon found that he couldn’t be seen by or interact with anyone, because no one believed in him. For three centuries, Jack tried to figure out who he was and why he existed at all. But he couldn’t get an answer from the Man in the Moon or make people believe in him, which made him grow increasingly frustrated and act as a mischievous loner. This attitude made Jack somewhat infamous as a troublemaker amongst other legendary figures.
One day, Jack caused a snow day in Burgess and tried to play with a boy named Jamie and his friends. However he was again frustrated by the fact that none of them knew he was there and again tried to ask the Man in the Moon for answers. Shortly afterwards, Jack ran into Bunnymund (The Easter Bunny), who had a bunch of North’s Yetis capture and bring him to the North Pole. There he was informed that he’d been selected to become one of the Guardians. Jack wasn’t interested in joining, but North convinced him to help for the time being, telling him about how each Guardian had a “center” that made them qualified. Jack joined them to help Tooth Fairy, who was under attack by Pitch Black. They arrived to find that most of her fairies had been captured by Pitch’s nightmares and they’d also taken all the children’s teeth. Jack managed to save one of the fairies, Baby Tooth, but the damage was done; with all the fairies unable to collect teeth, children stopped believing in Tooth. Jack also learned that he’d once been human and Tooth had his teeth, which carried his memories and became determined to stop Pitch, so as to find out who he had been.
Meanwhile, to try and keep things from getting worse, Jack and the rest of the guardians collected the teeth themselves, eventually ending up in Jamie’s room. However they accidentally woke him up and as Sandman tried to put Jamie back to sleep, his sand accidentally knocked out everyone except himself and Jack. The two set off in pursuit of one of Pitch’s nightmares, but were lured into a trap and desperately fought Pitch. Eventually Sandman was overwhelmed and was killed, causing Jack to angrily attack Pitch and unleash a massive freezing attack against his black sand. The Guardians and the boogeyman withdrew for the time being with the guardians mourning for Sandman, especially Jack. They then decided to help Bunnymund pull off the best Easter ever to try and restore the children’s belief. He brought Jack and the others to his home, the Warren, to get things rolling, where they found Jamie’s toddler sister, Sophie, who’d used one of North’s portal snow globes. While the other guardians saw her as problem, Jack, having spent so much time around actual children, was less bothered and used her to help the Guardians reconnect with the children they protected as they readied the eggs. Afterwards, Jack brought Sophie home, but before going back to the Warren, he heard a voice that he recognized calling his name. He followed it down into Pitch’s lair where he found all of Tooth’s fairies and the stolen teeth, before he faced off against Pitch himself, who preyed on his insecurities about not knowing his purpose and encouraged him to stay out of the fight in return for his memories. Jack refused, but Pitch gave him his teeth anyway, having delayed him enough so that his nightmares could destroy all the eggs, ruining Easter and shattering the children’s belief in Bunnymund. Angry at himself, Jack fled to Antarctica where Pitch approached him, saying that he knew how Jack felt and offered that they join forces. However he refused, wanting to be believed in, not feared, and Pitch revealed he had Baby Tooth, threatening to kill her if Jack didn’t give up his staff. He did so and Pitch snapped his staff, before knocking him into a crevasse. Jack gave up hope, until Baby Tooth had him see his memories, allowing him to realize that he’d been made into a Guardian by the Man in the Moon because of his heroism. Instilled with new hope, Jack fixed his staff and flew off to stop Pitch.
Jack headed to Pitch’s lair to free the fairies, but found that they couldn’t fly since all the children had stopped believing, except for Jamie. He headed to Jamie’s home, where the boy was just giving up his beliefs. However Jack managed to use his powers to convince Jamie to keep believing and even managed to make him believe in Jack. Jack was ecstatic that someone finally believed in him and the other Guardians arrived to help him fight Pitch. However they were all severely weakened and in no state to fight, but Jack, determined to protect Jamie, remembered how he had saved his sister and realized that his center was fun, namely being able to use fun to overcome fear. Jack evaded Pitch’s nightmares, as he gathered Jamie’s friends and restored their beliefs. Jamie stood up to Pitch, overcoming his fear, and restoring Jack and the other Guardian’s powers, as well as reviving Sandman. They defeated Pitch, who was dragged back into his lair by his own nightmares and Jack was sworn in as an official guardian. Jack wished Jamie goodbye, telling him to keep his belief in the Guardians in his heart, and left with the others to perform his role protecting the children of the world.
Jack is a mischievous loner, who refuses to obey any rules, but still has a gentle and good heart. He spends most of his time using his winter magic to amuse himself and the children of the world. Jack’s frustration with establishment and anti-social behavior is a result of the Man in the Moon never answering his questions as to why he exists, reinforced by the fact that no one believes in him. However Jack’s time with the other Guardians have brought out his heroic qualities, most notably his refusal to give up no matter the odds, and his good heart.
Jack is immortal and has the power of winter, which he channels through his staff. He can use this to generate frost on objects by touching them, create and manipulate ice and snow, and send out freezing energy blasts. Jack can also manipulate cold winds, which enables him to fly, and enchant his snow so that it makes anyone it touches be instilled with a high sense of fun.
Jack is both the Guardian of Fun and the Spirit of Winter, surprisingly powerful and a cunning trickster. It's his job to make children have fun, while bringing joy and fun times with Winter and snow days, thereby making them happy and bolstering their faith in the Guardians.
As the Spirit of Winter, Jack commands snow, ice, frost, and later learned he can unleash energy bolts of ice, and he can easily freeze things over/solid with a mere wave of his staff. Originally, Jack channeled his Winter Magic through his staff, mistaking it to be the source of his power, when really it was just a conduit. Jack can conjure ice, snow, and frost from his mere presence, as well as freezing winds, snowballs, snowflakes, etc. Jack can even manifest images from frosted window panes, freeze water by walking on it, and conjure indoor snowfall, and of course, being the spirit of winter, he is not bothered by the cold.
Jack is able to fly by riding the wind. He flies by floating like a snowflake, and propels himself with wind to fly faster.
Magic of Fun
As the Guardian of Fun, Jack can bewitch others with feelings of fun, joy, and laughter with his snowballs or even his snowflakes. This was first seen when he hit Cupcake with a snowball, quelling her anger, and helping her have fun and become friends with Jamie and the other kids.
Jack is a very skilled free runner and can quickly move across rooftops or even weave through traffic with uncanny speed and agility, as he safely directed Jamie on an epic sled-ride.
 Jack has a magic staff with which he can control the elements of winter. Originally, he thought this staff was the source of his power, when really it was just a conduit for him to channel the magic of winter that had really been inside of him, seen when he repaired it through sheer force of will after Pitch snapped it in half.
- The origins of the legendary Jack Frost comes from Norse mythology and he is also known by the names of Father Frost, Old Man Winter, and Jokul Frosti.
- Jack has a history with Bunnymund, having apparently caused a huge blizzard on Easter Sunday in ‘68.