Robbie Valentino

Robbie V is Wendy's ex-boyfriend, who first appears in "Headhunters." His greatest claim to fame is a giant explosion he spray-painted on the water tower (along with other spots around Gravity Falls), which Dipper thinks is a giant muffin. Because of this, and the fact that Dipper also likes Wendy, Robbie grows to dislike Dipper and tries to exclude him from the group due to his age and liking of Wendy. He is voiced by T.J. Miller.

History
Robbie is first seen in a picture on Dipper's suspects board in "Headhunters." He makes his first physical appearance in "The Inconveniencing", driving up with Wendy's other friends to pick her up. He boasts to Dipper about spray painting an explosion onto the water tower. When Dipper points out that the image looks more like a muffin then an explosion, Robbie glares at him. Robbie takes the passenger seat on the ride to the Dusk 2 Dawn convenience store, pushing aside Dipper and saying he "always rides shotgun." During the group's stay at the store, he acts very condescending towards Dipper. He makes fun of Dipper when he hesitates to jump the fence, and doesn't think Dipper can get them inside the store when Robbie's efforts to open the door prove to be pointless. Once Dipper gets the kids inside, he is seen partying with the rest of them. When the ghosts attack, he is one of the only teenagers not to be taken. However, he is not seen when Dipper does the Lamby Lamby Dance to save the group.

Robbie then appears in "Double Dipper" at the Mystery Shack party hanging out with Wendy. He ignores Dipper and shows Wendy his new guitar. Seeing him as an obstacle between him getting to dance with Wendy, Dipper and his clones lure Robbie away from the party by stealing his bike. However, at the end of the episode, Robbie comes back and chats with Wendy, ruining Dipper's plan.

Robbie starts dating Wendy in "The Time Traveler's Pig," which sets up the plot for Dipper to start time traveling to prevent it. Later, when Dipper successfully wins Wendy a stuffed animal, Robbie becomes jealous and walks away, pretending to not care. When Mabel's enemy, Pacifica, wins Mabel's pet pig, Dipper decides to time travel back again after he realizes he'll break Mabel's heart if he doesn't. This causes Robbie date Wendy at the time.

In "Fight Fighters," Robbie has officially started being Wendy's "boyfriend". While putting up flyers for his band, Robbie notices Dipper's crush on Wendy, and he tries to call Wendy to tell her Dipper's secret. However, Dipper breaks Robbie's phone to prevent this from happening, causing Robbie to challenge Dipper to a fight at 3:00. When Dipper unleashes Rumble McSkirmish from an arcade game, Dipper uses Rumble as a bodyguard to scare off Robbie and put a stop to the fight. When Rumble encounters Robbie, he nearly kills him. Dipper tries to stop Rumble from seriously injuring Robbie, and he successfully does so by facing Rumble in a battle. Robbie decides not to fight Dipper afterwards, and the two decide to hate each other in silence, rather than to physically show their anger.

Robbie is seen again in "Summerween", visiting the Mystery Shack with Wendy. The two inform Dipper of a party later that evening (though Robbie doesn't seem very enthusiastic about telling him). Robbie seems extra moody in this episode; he spends most of his screen-time talking down to Dipper, and is even punched in the arm by Wendy because of it. In the end of the episode, Wendy mentions him again; Robbie had to leave the party early, because he swallowed a lollipop stick-first and got sick.

In "Boyz Crazy," Robbie didn't show for a date he had planned with Wendy, then comes into the shack the next day and asks if she would like to go to Lookout Point with him, to which she reacts angrily. She begins talking about breaking up with him, and, panicked, he takes out a CD of a song he ripped off from some band and plays it for her, claiming he wrote it for her himself. She is willing to go with him after this, and is happy. Dipper, however, is suspicious and ends up finding a hidden message in the song and playing it for Wendy and Robbie on their date. Robbie immediately tells Wendy that he had no idea that message was there and that he ripped the song off from some other band anyways, thinking that will fix the problem. Instead, she becomes furious with him and breaks up with Robbie on the spot.

Personality
In terms of personality, Robbie is a stereotypical moody teenager: Laid back and apathetic. He is seen as condescending to people younger than him, as shown by his interactions with Dipper. In "The Time Traveler's Pig," he asks Wendy to go out with him and she agrees, right in front of Dipper. Robbie is anxious to date Wendy just like Dipper, and seems very nervous about asking her out. Robbie loves feeding his ego. In "Fight Fighters," Robbie boasts a lot, and doesn't hesitate to show off. (i.e. He makes sure to mention the fact that Wendy is in fact his girlfriend, he boasts about his band, he belittles Dipper, etc. etc.).

Appearance
Robbie has black hair in a typical eye-covering "emo style", pale skin and piercings. Like some characters on Gravity Falls, he has a pink nose. He has been seen wearing a black guitar around his chest. He usually wears thight skinny jeans with several keychains from the pockets. He also wears a black hoodie with a picture of a red bleeding heart with a scar on it and stitches, along with black fingerless gloves. He has a sparse stubble (two strands of small hairs) on his chin, and a few pimples scattered around his face.

Dipper Pines
Since the first time Robbie met Dipper, he has been condescending and arrogant around his younger counterpart, making fun of virtually every trait about him and everything he does. In a short while, they begin competing for Wendy's attention, highly angering and upsetting Dipper when he began a relationship with her. During this time, Robbie made sure to brag to and about Wendy at every possible instance around Dipper, with the two never stopping their feud, even in front of Wendy (save for their short-lived "Cold War pact"). After a time, their brawling cost Robbie his relationship and possibly Dipper's friendship with their crush.

Mabel Pines
Robbie and Mabel lack a formal rivalry, but nonetheless are enemies. Observing the teenager's snobby attitude, she sees him as a jerk, being an object of ridicule herself on occasion. Since Mabel gets entangled in her brother's love life, she has been known to sabotage Robbie to help Dipper in his quest to win Wendy's love, although she becomes less concerned with this over time.

Wendy Corduroy
The two have been friends for some period of time and like to hang out. Despite his typically careless attitude toward other people, he expresses some concern for Wendy, though this is highly limited. Robbie has feelings for Wendy and managed to maintain a short-lived relationship with her, though this fizzled out after a few weeks, due to his arrogance, negligence and dishonesty.

Lee, Nate, Tambry, and Thompson
Robbie enjoys venturing off to spend time with his rowdy friends, particularly bonding in miscellaneous antics with his fellow males. Their visits to one another are frequent, and their activities are not always in compliance with the rules.

Trivia

 * In "Double Dipper", Dipper clones 3 and 4 stole Robbie's bike, but didn't return in the episode.
 * The stitched heart logo on his jacket appears in the opening song "Made Me Realize" on a photo of a page of the journal that has to be freeze framed to see along with other symbols supposedly associated with other characters.
 * Robbie's band is called Robbie V. and The Tombstones.
 * Robbie was in the list of unhappy suspects in "Headhunters".
 * Similar "Explosion Muffins" to the one that Robbie spray painted on the water tower appear through out the show in various backgrounds, most noticeably in the enclosure around the water tower.
 * His last name starts with a V as revealed in "Fight Fighters".