Dipper Gleeful

Mason "Dipper" Gleeful is one of two main antagonists of the Disney's 2017 animated film, Gravity Falls: The Movie.

Personality
Like his sister, Dipper has a lust for power and enjoys the pain of others. He's often seen to be either cold and unfeeling, or simply disgusted by the affection or caring of others. Seemingly, the only person he shows any sign of actual care for is his sister/partner Mabel, but even that has its limits.

Dipper is extremely intelligent and sly, being able to fool the town into believing him to be a kind and benevolent young man. He has little trouble manipulating others into doing or getting what he wants. This makes him a great threat, with or without his amulet.

However, unlike his sister, Dipper is seen to be slightly more stoic, serious and more disgusted by those he deems pathetic or weak, instead of sinisterly amused like Mabel is shown to be.

Mabel Gleeful
Mabel is Dipper's twin sister and partner in crime. She has been speculated as the only one he cares for in Reverse Falls. At the very least, he does show a great deal of respect for her powers and he does show signs of immense care for her. He identifies the two of them as partners. Even though they have shown to irritate each other at times; they are mature towards each other and are shown to love each other regardless.

However, Dipper is often annoyed by his sister's constant enthusiasm towards their victims' pain and doesn't like it when she is distracted or not on task. His serious nature can sometimes frustrate Mabel, who often deems him a 'killjoy'.

Dipper's love and care for Mabel is shown in many fan-art. It's often depicted that when Mabel is hurt, Dipper will either cry for her and/or torture the culprit. He is shown to have a sort of protective complex, as he will attempt to protect her from any danger, regardless of whether or not she can look after herself. Dipper is shown to be frequently agitated when boys pursue Mabel's attention, seeming them as foolish or a threat. He considers his sister as a showoff, and (though he won't admit it) he thinks she's too good for them. They have a similar relationship to the show's Pines twins, just with more restraint and won't admit they love each other like the Pines twins do.

It should be noted that Dipper is slightly fearful or at least disturbed by his sister's overly violent, sadistic amusement and pleasure of their victim's torture.

Pacifica Southeast
The twins are famous for their show and tricks. After frequent visits to their shows, Pacifica Southeast has developed a secret crush on Dipper. At first, it amuses him to the fullest but later Mabel tries to use it to their advantage, seeing as Pacifica doesn't know their true character anyway.

However, over time Dipper becomes less aggravated by Pacifica's positivity, and more confused by her perseverance. Moments when Pacifica displays her intelligence, Dipper is seen impressed, or at the very least intrigued, and when she tries to drag him into her adventures and ideas he usually politely declines and at rare times go with her only to leave shortly after the fact. Overall, it's to be noted he doesn't wish to physically harm her.

Mabel takes note of this and confronts her twin brother, going so far as to openly command him not to fall for Pacifica's 'goody-goody words'. Dipper assures her that everything is under control and Mabel carries on with the plan on how to take Journal 3 from Gideon.

In many fan-fictions it has become popular for Dipper and Pacifica to be together; however this is not canon.

Gideon Pines
Both of the Gleeful twins' first meetings with Gideon are through his appearance at their show, however when they properly speak to each other, both mention they had already known about a 'new kid' coming to town before hand. When Gideon questions how they knew that, Dipper calmly explains that "We know everything. Nothing happens in this town without our knowledge first."

At first Gideon is only mildly jealous of Pacifica's adoration over the Gleefuls, Dipper specifically, but when he finally meets them and starts to suspect them, Gideon becomes agitated and more determined to prove the twins' true intentions. When those intentions are shown to be more diabolical, Gideon claims he must defeat them and protect the town. (Note: Pacifica's constant refusal to give up on Dipper and Mabel fuels Gideon's rage further.)

Gideon and Dipper (similar to their Gravity Falls counterparts) are in a bitter rivalry, and tend to despise each other immensely. When Gideon tries to stand up to Dipper, the latter becomes angry over his 'disrespect' and tries to threaten him, but Gideon refuses to back down. Eventually when the twins' start connecting Gideon to other strange occurrences, Dipper sees Gideon more of a threat to their plans, rather than just a threat to his pride. Time and time again, Gideon has been shown to be able to hold his own against whatever the twins' throw at him, only making Dipper angrier and vow to destroy Gideon at all costs.