When Belle becomes pregnant with Rumplestiltskin's baby, she learns that Rumplestiltskin owes his secondborn child to Hades. To protect her unborn child, Belle puts herself under a Sleeping Curse, preserving mother and child together. In the dream world, Belle is able to communicate with his son, although she is unaware that he is her son, as he pretends to be Morpheus, the god of dreams. As Morpheus, he warns Belle to stay away from Rumplestiltskin, before kissing her on the forehead, awakening her in real life. When Belle gives birth to her son, she names him Gideon after the hero of her favorite book. Desperate to keep her son away from Rumplestiltskin, Belle has the Blue Fairy take Gideon somewhere safe. While transporting Gideon, however, Blue is ambushed by the Black Fairy, who takes him back to her realm. He is trained in magic, and becomes the Black Fairy's "son". However, when Gideon begins to rebel against her, the Black Fairy rips out his heart - ensuring his loyalty - before instructing Gideon to travel to Storybrooke and kill the Savior, Emma Swan.
Twenty-eight years later, Gideon leaves the Black Fairy's realm, returning to Storybrooke. After trapping the Evil Queen in the form of a caged cobra, Gideon visits his parents. As time works differently in the Black Fairy's realm, however, his parents only learn about Gideon's abduction moments before Gideon returns as an adult. Gideon claims that he has returned to kill Emma and become the new Savior to kill the Black Fairy, who took him in the first place. When Emma returns from the Wish Realm, she and Gideon face off. Despite Emma's visions, she emerges victorious and Gideon vanishes, later destroying the clock tower. With his father's help and the Blue Fairy's blood, Gideon restores Hrunting, the sword destined to kill Emma Swan. He later banishes Hook on the Nautilus, blackmailing Emma into helping him kill the Black Fairy. However, Gideon is revealed to be under the Black Fairy's control, and needs Emma vulnerable enough to use her life force to open a portal to the Black Fairy. He fails to kill her, but enough life force is used to open a portal, bringing the Black Fairy to Storybrooke.
When Rumple learns that his mother has Gideon's heart, he manages to contain Gideon and his magic, before submerging both of them into the dream world so they can speak without Gideon being controlled. Gideon does not know where his heart is, but Rumple secretly allies himself with Fiona and returns Gideon's heart to his son. However, when Fiona releases her new curse, Gideon's heart once again belongs to her. Under the curse, Gideon works at the pawnshop with Rumplestiltskin, after Belle allegedly abandoned them. When Fiona needs her wand, she controls Gideon into finding it for her. Once again powerful, Fiona orders Gideon to find and kill Emma Swan once and for all. Even Fiona's death at the hands of Rumple does not prevent the Final Battle from unfolding, and Gideon battles Emma, although Emma eventually gives in and allows Gideon to strike at her with his sword. However, instead of dying, Emma unleashes a blinding flash of light. When Fiona's curse is broken, Rumple and Belle find a baby in a basket, and realize that fate has given them another chance to raise Gideon.
Gideon learned dark magic from the Black Fairy, and possessed an array of powers before his "reset":
- Transformation: Gideon can transform other people, or objects, into something different.
- Telekinesis: He can also telekinetically move people and objects.
- Teleportation: Gideon has displayed the ability to teleport from one place to another.
- Glamour: Gideon can disguise himself as other people, such as David.
- Rumplestiltskin (father)
- Belle French (mother)
- Baelfire (deceased half-brother)
- Henry Mills (nephew)
- Cinderella Mills (niece-in-law)
- Lucy (great niece)
- Reul Ghorm (godmother)
- Maurice (maternal grandfather)
- Colette (deceased maternal grandmother)
- Peter Pan (deceased paternal grandfather)
- Fiona (deceased paternal grandmother/deceased adoptive mother)
- He is the son of the beauty and the beast from the fairytale Beauty and the Beast.
- When disguised, he claimed to be the god of dreams from Greek Mythology.
- Gideon is named after a hero in Belle's favorite childhood book, Her Handsome Hero.
- Gideon is the hooded figure in Emma Swan's visions, supposedly destined to kill her.
- S6, E01: "The Savior" (vision)
- S6, E02: "A Bitter Draught" (vision)
- S6, E05: "Street Rats" (vision)
- S6, E09: "Changelings"
- S6, E10: "Wish You Were Here"
- S6, E11: "Tougher Than The Rest"
- S6, E13: "Ill-Boding Patterns"
- S6, E14: "Page Twenty-Three"
- S6, E15: "A Wondrous Place"
- S6, E16: "Mother's Little Helper"
- S6, E17: "Awake"
- S6, E18: "Where Bluebirds Fly"
- S6, E19: "The Black Fairy"
- S6, E21: "The Final Battle, Part One"
- S6, E22: "The Final Battle, Part Two"