Shadow Julian is a truly evil counterpart to Julian, created by the corruptive influence of the Sorcerer's Chaos Pearl, bringing every part of Julian's darker side to life and giving it dangerous powers.
In "Julian's Birthday Surprise" during Julians birthday, Jullian had it at a great stage magicians show. However he was miserable at his own failures at learning to illusions, and after Howard told him he couldn't get worse, Randy went to comfort him, Julian began a long life story. However Randy slipped into the Nomicon while he was talking. During this Julian found and took Randy's bag containing one of the Sorcerer's Chaos pearls believing it to be his birthday present. The orb's evil power began to corrupt him, Randy managed to get it back but not before Julian had gotten a taste of its power. During the show, Jullian managed to get the stage magician to involve Randy in a trick allowing him to steal the Pearl. The Pearl then empowered him giving him genuine magical powers, but also corrupted him and drove him insane as the power has bonded with the darker side of his personality.
He attacked the show, driving the stage magician away, before bringing the gargoyles to live and turning the robot on the guest. Using his new power he opened up a doorway to the Shadow Realm, planning to throw his guests in. However Randy fought back and managed to save them. As the creatures from the realm of shadows tried to pull him in, Randy managed to swipe the Pearl from Julian. Howard managed to retreave it and offered it to Julian in exchange for freeing Randy. Julian agreed but Howard threw the bag, and grabbing it Randy threw it into he portal. Julian tried to jump into get it back, but Randy managed to pull him out, as well as forcibly seperating the corrupted part of him created by pearl in process. Saving the real Julian who awoke unsure what had occured, while his evil counterparter (the embodiment of his darker side that has bonded with powers of Chaos Pearl) was trapped in the land of Shadows. It was there he learned Howard had tricked him and the bag only had one the gargolyes heads in it.
Shadow Julian returns in "Snow-Klahoma" now starking and terrifying his real counterpart, using mirrors to contact him from the land of Shadows, planning to use him to allow him to enter the real world. Julian bonded to Randy to keep himself safe, but sick of Julian constantly messing up all there fun, Randy agreed with Howard to ditch him in the ice maze, unknowningly leaving him vunerable. Shadow Julian suceeded in kidnapping his counterpart and used him to switch places, allowing him back into the real world.
His first act was to turn into a giant monster and start terrorising the area, mistaking him for the real Julian turned into a monster, Randy fought him. But the fight proved impossible, as there was no way to change him back. Randy was forced to chose between letting him go or freezing him in liquid Nitrogen, however as this had achieved his aims Julian returned to normal (what they were isn't presently unclear) and causally left. Randy none the wiser to the great danger that was free. As he walked down the street, he happily caused all the lights to stop working.
From there, Shadow Julian realized that because Ninja's presence, he cannot causing much chaos as much as he desires. So, he goes to collect all of the Chaos Pearls to compensate this. Over the course of this schemes, he taunts his human self that he previously sealed inside the Land of the Shadows, in which caused Randy and Howard realized that they now dealing with Julian's evil counterpart. In the end however, he eventually destroyed once being absorbed by the real Julan.