Gideon Pines

Gideon Pines is one of the main protagonists of the Disney's 2017 animated film, Gravity Falls: The Movie.

Description
Gideon has albino white hair and is usually depicted wearing clothing similar to Dipper Pines from the show Gravity Falls; only with a light blue and black color scheme, rather than orange and dark blue. However, he does share the same blue pine-tree hat. Like his counter-part Gideon Gleeful, he's also very short, and the shortest amongst the main characters.

His face is covered in small dark colored freckles with a constant pinkish blush on the cheeks, and is quite plump compared to the other individuals in Reverse Falls.

Personality
Gideon is generally considered to be very kind and gentle with most people, except when it comes to the Gleeful twins. He is incredibly suspicious of them and considers them as his rivals, though he would not hesitate to be nice to them if it means getting answers.

He's also noted to be fairly intelligent, and has quick instincts that help him when something is wrong, allowing him to solve the mysteries of the town.

Gideon is often represented as a bit shy, insecure, and having some social anxiety, as his parents, Mr. and Mrs. Pines, are frequently noted to be abusive, lowering his self-esteem.

Pacifica Southeast
Gideon's cousin is Pacifica Southeast. He moves in with her because of family issues back home, and since then she has become his closest companion. Pacifica always invites Gideon for a walk and partying.

Gideon rarely shakes his head to her, even when Pacifica is acting weird. Gideon has been shown becoming nervous if Pacifica is not around, her bubbliness and positivism giving him confidence.

At times, he has been shown to be the one to calm her down, whenever she gets in-over her head.

Dipper Gleeful and Mabel Gleeful
Ever since he first saw their show, Gideon has been suspicious of both Dipper Gleeful and Mabel Gleeful. Who also becomes suspicious of him as well, and later begins to see him as a threat to their plan.

Because of this, Gideon begins to fear them, but tries his hardest to stay strong in front of them, and show no fear.

Both twins have two different views on him. Dipper finds Gideon to be a nuisance and annoyance, especially whenever Gideon tries to stand up to him, but decides in keeping him alive due to his own suspicions about the 'new kid in town'. However, this also means Dipper will do what he can to keep Gideon in line.

Mabel, however, finds him more amusing and interesting, going so far to even tongue-twist him into a date with her. Her attraction to Gideon is originally for her own amusement and overtime becomes suspicion over his intentions in Gravity Falls.

William Cipher
Will is a dream demon that was originally summoned by the Gleeful twins to help rid them of their 'new kid problem', (that being Gideon).

At their first encounter, Gideon's initial reaction was fear, but he quickly realized that Will is very submissive and benevolent by nature, causing Gideon to become confused when Will began crying. After calming down, Gideon tried (though awkwardly) to be civil with the demon, and tried to ask him questions about the universe (though fearful he may upset Will again).

Eventually, Will fails in his mission, angering the twins and sealing his fate as their slave. Due to the way he was treated with Gideon and Pacifica, it's possible he failed on purpose, so as to not harm them. After this, Gideon's interactions with Will are rare, but when they do meet, Will is quick to help him in whatever way he can. Usually, this is in the form of a warning against certain magical creatures Gideon has encountered or tries to find, and to be wary of the twins.

Trivia

 * It is shown in the official series that Gideon white hair was caused by the amulets by a page from journal number 2 saying that the amulet corrupts the soul and turns hair white.