Mason "Dipper" Gleeful is the alternate version of Dipper Pines from the show Gravity Falls. He and his twin sister Mabel Gleeful run the Tent of Telepathy and are considered "villains" to the main protagonists, Gideon Pines and, in a way, Pacifica Southeast.
Before you read this, note that the situations, personalities and more are based on how the different fan-fictions and takes of Reverse Falls are usually written. It may vary according to another’s opinion.
Dipper is an exceptional and charming version of his canon-counterpart. He has blue eyes and polished clothing and is complimented (like his sister) in shades of blue, and is sometimes complimented with a white piece. He's widely seen in a light blue shirt with black trousers and a belt. He sometimes wears a cape, with the symbol of the Tent of Telepathy of the twins on the back.
In some fan-art, he is seen to be wearing a pair of blue earrings, similar to his twin. Just like Mabel, he always wears his amulet, his being in the form of a bolo tie.
Compared to the cartoon show, Dipper's first and real name is Mason but gets the nickname "Dipper" from a birthmark on his forehead that resembles the big dipper constellation. Unlike his Gravity Falls counterpart, he is uncaring for the mark, and doesn't worry about people judging him for it and therefore doesn't bothers to cover it up. This has often depicted him as having his hair brushed or slicked back, as he prefers it better.
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.Both Dipper and Mabel are obsessed with magic, specifically black magic, and will use their shows as means to continue their studies about the magic and anomalies in Gravity Falls. It can be assumed that Dipper, as well as his sister, are sociopaths and have some levels of emotional detachment as, with his sister, they will secretly kill and/or use the people who 'volunteer' during one of their shows. The one who volunteers will be given a challenge. While the audience is still watching, Dipper and Mabel will use their powers to make the volunteer look 'alive' by making them move even when they're already dead. This can also imply that they are quick-thinking and cunning, as they never get caught.After the show, when the audience is gone, he and Mabel will secretly hide the volunteer's body to later use in magical practices and experiments.
Mabel is Dipper's twin sister and partner in crime. She has been speculated as the only one he cares for in Gravity 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 guys dribble over Mabel, seeing them as foolish. 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.
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 positivism, 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.
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: Paicfica'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.
Will is often shown to be used both for his powers and for his vast amount of knowledge by Dipper and Mabel. Will is usually also tortured by the twins and have often been seen sobbing in corners about how his life is miserable and how Bill calls him a loser and a pushover.
Dipper seems to have no problems being cruel to him and is even happy doing so, much to Will's misery. This could be because, unlike human victims, Will cannot be killed, and there is nothing lost in torturing him. Dipper can revel more in the fact he has so much control over a powerful dream entity rather than that of ordinary humans or other lesser creatures. Will has also been seen as the victim of Dipper's pent up frustrations, whether or not the problem is even Will's fault. Dipper is notably much crueler to Will than his sister Mabel is.