Julius is the deuteragonist in The Flight Before Christmas and its sequel Little Brother Big Trouble: A Christmas Adventure. He is the best friend and father figure of Niko. He was voiced by Hannu-Pekka Bjorkman in the Finnish version and Norm MacDonald in the English redub.
Julius is good-hearted, but also a bit of a clumsy flying squirrel. A long time ago after losing his wife, son and aunt Sally to a pack of hungry wolves, Julius found his new home amongst the reindeer herd. Julius is Niko's best friend and has acted as a father figure and mentor for Niko, taking care of the boy through thick and thin. Julius likes a quiet life but he rarely get it as he often gets dragged into exciting adventures with Niko.
Julius first appears when he is riding on Niko who is watching the Flying Forces test fly. Niko then attempts to fly like his father (who is one of the Flying Forces), but fails and is laughted at and teased by two younger reindeer children. Julius tells Niko to ignore them and leave, but when the two reindeer children continue to call out taunts at Niko, Julius throws snowballs at them to make them stop.
Niko plans to leave Home Valley and go to Antler Hill, though Julius tries to convince him not to. Just then, Niko's friend Saga appears, having heard Niko talk about Antler Hill. This also attracts the attention of Saga's father the herd's leader who forbids Niko to go to Antler Hill as Home Valley is the only place the herd are safe from wolves. However, after the Leader leaves, Niko and Saga agree to go to Antler Hill the next day. That night, Julius listens to Oona telling Niko about how she met his father.
The next day, Julius catches Niko along with Saga outside Home Valley and tries to get them to go back, but to no avail. Soon enough, two wolves named Smiley and Specs appear causing Niko and Saga to run back to Home Valley, while Julius says behind to distract the wolves. Following the Leader getting hurt whilst dealing with Smiley, the herd are forced to find a new home and Julius accompanies them. Julius notices that Niko isn't in the herd (as he left after hearing the herd talking about him), Julius tells Oona that he will find him.
Julius finds Niko, who is heading to Santa's Fell to find his father. Julius tries and fails to convince Niko to return to the herd and goes with him to Santa's Fell and along the way, they meet a weasel named Wilma, who Julius takes an instant dislike to. Julius and Niko have a run in with Black Wolf and his pack, but are saved by Wilma. Wilma leads the two to Santa's Fell and attempt to cross The River of Certin Doom, but run into the wolves again and Niko falls down the river, but Julius and Wilma save him.
Whilst Niko rests, Wilma sees Julius making snow squirrels who says they are his wife, son and Aunt Sally. Julius tells Wilma that one day when he was out, his real family was killed by wolves and that Niko is his only family, until he finds his father. Wilma tells Julius that her family didn't want her to be a singer, so she left, this conversation finally makes the two bond. Niko wakes up and says that he had a nightmare where wolves attacked his herd and eat Oona and Saga, to which Julius comforts him. The trio arrive at the labyrinth that will take them to Santa's Fell, where they go they take a shortcut and get to Santa's Fell and Niko races ahead to see the Flying Forces. Julius and Wilma arrive at the Flying Forces' mess hall where they reunite with Niko and Wilma sings a song to the Flying Forces to ask which of them is Niko's father, but they say none of them have kids or remember meeting a reindeer named Oona. As the Rio begin to leave, Julius says to the Flying Forces that none of them deserve to be Niko's father. Dasher says that Niko can take a flying test to see if he is a son of one of them.
Niko nearly succeeds in the flying test, but Julius's screaming distracts him and causes him to fall out of the air, but is saved by Dasher. Feeling dejected, Niko leaves and gets into an argument with Julius and says that he can't tell him what to do as he is not his father, before storming off. Just then, Black Wolf and his pack arrive and prepare to kill and eat the Flying Forces, who in panic lose their flying powers. Julius flies on Prancer (who has a box on his head and regained his flying ably) and convinces the other members of the Flying Forces to help Niko defeat the wolves which they do. Using the sleigh, Julius and the Flying Forces save Niko (who falls from a tree whilst being pursued by Black Wolf), but Black Wolf comes onto the sleigh too and tries to attack Niko.
Julius sacrifices himself to save Niko by release in the part of the sleigh Black Wolf is on, taking Julius himself with him. As he falls, Black Wolf attempts to eat Julius as a last meal, but Niko flies to save Julius and chases the rest of the pack away and learns that Prancer is his father. Julius along with Wilma sit on Santa's sleigh and watch Niko fly with the Flying Forces to which Julius believing that Niko is happy with the Flying Forces now, flies back to the herd and tells them that Niko can fly and has joined the Flying Forces, but they don't believe him and Oona is angry with him for not bringing Niko back, with only Saga believing the story.
Just then Niko returns with Wilma and reunites with Oona. Julius witnesses Niko turn down an offer by Prancer to join the Flying Forces, to remain in the herd and stay with Julius (who Niko sees as his father), but promises to visit Prancer after Christmas. Julius is last seen when he and Niko lead the herd to a new home with plenty of food and water as he and Niko fly in the sky.