|"You were built to protect those who cannot protect themselves."|
|— Dr. Julien to Zane|
Dr. Julien created Zane in his Hidden Workshop. As time passed, he taught Zane how to walk, speak, and perform other basic human activities, such as cooking and housekeeping. He also built the Falcon to serve as a companion for his creation.
Eventually, Dr. Julien's health began to fail as he grew old. On his death bed, he told Zane "The only reason I'm about to do this is because I love you" before turning off his memory switch, making Zane forget about his past.
Later, Zane finds out he is a Nindroid and turns on his memory switch. It appears that he created Zane because he did not have a family of his own, and grew to love him as a son. Knowing this made Zane feel stronger, which helped him unlock his True Potential against the Treehorn Queen.
The Last Voyage
When the Ninja set sail in the broken Destiny's Bounty toward theIsland of Darkness, Zane senses they are approaching an island before they crash onto the shore. They get off to investigate and spot a tall tower, with Zane calling it a prison. Dr. Julien opens the door excitedly upon seeing them, happily greeting his son and rushing them inside after mentioning an unspoken of threat outside.
Dr. Julien barricades the front door and looks around the island through a small camera, and after announcing that it is safe, he escorts them upstairs. He tells his guests to take a seat and sends a small robot to hand out cups, pouring tea for them afterward.
Zane spots his blueprints and questions how his father could be alive. Dr. Julien tells him that once he had passed away, Samukai revived him with a special elixir, yesterday's tea, commanding him to make the Skulkinwar machines. Although he refused at first, Samukai stranded him on an island in the prison and placed theLeviathan as guard, telling him that he would be able to see Zane again if he complied. Dr. Julien says that he wanted to see his son again, but was afraid that Zane would think he was a monster for creating the Skulkin machines.
Zane promises him that he will figure out a way off the island, and Jay asks if Dr. Julien could repair the Destiny's Bounty. He tells them that he would have the Bounty repaired by dawn, but once they hear the growling of the Leviathan, Dr. Julien orders the Ninja to hide. The Leviathan looks into the prison, and after seeing that everything is normal, leaves.
After they work on the repairs until nightfall and have dinner, Zane asks his father if he could make an adjustment in himself to remove his memory switch. Dr. Julien assures him that he is perfect the way he is, though Zane says that he likes his life and would not want to forget about him again. Dr. Julien tells him that neither of them will forget and that he is glad Zane found him, and as they hug Zane replies saying that he is thankful that he was created.
The two suddenly hear the Leviathan approaching, and they quickly rush to the Bounty to inform the Ninja to escape. They all get on board, and as the Bounty begins taking flight, the Leviathan's tentacles grab onto the ship. Lloyd uses his powers in an attempt to release the monster's grip, which works temporarily before it grabs onto the ship again. Zane spots a chain attached to the creature and decides to unchain it. Despite his father's warnings, he jumps off the Bounty into the sea, swimming down where the Leviathan's chains remain and using the Starteeth to gnaw through the metal. Upon being released the monster stops attacking, and once Zane climbs back on the Bounty he explains that not even a monster deserves to be held captive.
Island of Darkness
When in need of vehicles to help with the fight against the Stone Army, Dr. Julien and Nya both work on building the Power Drill and Fire Robot.
Later he is seen in the Destiny's Bounty with Sensei Wu and Misako as they witness the Stone Warriors retreating from the Temple of Light.
The Last Hope
As the Ninja are celebrating the restoration of their powers on the beach, Dr. Julien finishes the repairs on the Falcon, allowing it to fly again.
Return of the Overlord
The Ninja return to the shore, Dr. Julien frantically questioning the sound of the horns in the distance. Sensei Wu explains to him that the Celestial Clock had reached zero and Lord Garmadon received the ultimate weapon, the Garmatron.
While the Ninja rush after Lord Garmadon, Dr. Julien requests to be left behind as he cannot keep up, assuring Zane that he will stay in the Destiny's Bounty before saying his farewells.
Later, as The Overlord uses the Garmatron to fire a missile at Lloyd, Dr. Julien arrives in the Destiny's Bounty and uses it to block the attack, abandoning the ship while it crashes.
Rise of the Spinjitzu Master
On the shore of the Island of Darkness, Dr. Julien helps bandage Lloyd's broken leg. He tells Lloyd that it is broken, and will take time to mend back. Afterward, he follows the Falcon alongside the Ninja to the Temple of Light.
When the Ninja used their four Elemental Blades to reveal the Golden Mech, he explains that time has rusted over the machine, but Lloyd manages to reboot it as he is the next Spinjitzu Master.
With the Mech and the Ultra Dragon, the Ninja and Dr. Julien return to Ninjago. He, Sensei Wu and Misako witness the Final Battle between Lloyd and the Overlord on the Ultra Dragon.
Death and LegacyEdit
Sometime after the Overlord was defeated, Dr. Julien died under unknown circumstances.
Dr. Julien was revered as a great inventor and as the creator of the first Nindroid. Cyrus Borg would later praise his work, saying that he would have fit right in the modern New Ninjago City. Ultimately, his legacy in the Nindroids would be tarnished when the Overlord used Zane's blueprints to create General Cryptor and his Nindroid army.
- He has the same hairstyle as Ed and Griffin Turner, though a different hair color.
- In "The Last Voyage," Dr. Julien told Zane that he never programmed him to cook, but in "Tick Tock," Zane's memories show them cooking a soup together (though likely, it's possible Zane picked it up as time went on).
- In "The Last Voyage," the prison tower Dr. Julien was imprisoned in is covered in "dashes," indicating Julien spent an incredibly long amount of time trapped there.
- It is quite possible that Dr. Julien was a descendant of the First Elemental Master of Ice, as seen that Zane's element is Ice. Dr. Julien may have never awoken the power due to never having to need it.
- The Last Voyage
- Rise of the Spinjitzu Master
- Tick Tock (flashback)
- Island of Darkness
- The Last Hope
- Return of the Overlord
- The Titanium Ninja (flashback)
- The Surge
- The Art of the Silent Fist