In the first half of the game, he is depicted as a young boy while in the second half, he is fully grown and running the shop in place of his brother. When he was a boy, Gideon was very attached to his mother and brother, and due to his youth was very childish and innocent. For a long time, he behaved like a spoiled child in front of his brother, and would flaunt his status as a younger brother as an excuse for his selfish words and actions.
However, after his mother disappeared, he became overly dependent on Jakob, so when he lost his brother through his own mistakes, his personality began to break down. He managed to keep his ego by making himself believe that the robot caused his brother’s death, and continued making strong weapons to exact his revenge on the robot. Also, he remembers ripping off his brother’s arm while trying to pull his corpse out of the debris, a memory that caused him much trauma. After that, he began injuring his own arm, eventually going overboard and requiring an artificial arm for his left arm. After seeing his brother's crushed body, he discovered P-33, a big robot, and developed an absolute hate for all robots for taking away his family. As time passed his hatred grew to a level of near madness, as he would chuckle at the thought of any robot being destroyed. Even when it was shown that a small Shade was involved in working the robot, he refused to accept that Shades were at all responsible.
In the second play through, it was revealed by P-33 that he and his Shade friend, Kalil, were not at all responsible for Jacob's demise. The boys loud voices caused the loose structure to topple on top of Jacob, effectively causing the events to Gideon's madness. Kalil, the Shade, expressed sorrow as it thought the two boys seemed kind.
During the initial inspection of the Junk Heap, it was revealed that his mother was killed by a gigantic robotic security system when she attempted to leave the boys to pursue a life of her own.
- Gideon is the only character to only cause the deaths of other characters. In his case, he caused a platform to crush Jakob and ordered the deaths of P-33 and Kalil, with P-33 surviving.
- Gideon shares the same voice actor as his brother in the English release.