At some point before the beginning of the series, Candy became best friends with Grenda.
The two go to the Party at the Mystery Shack together in "Double Dipper." There, they meet Mabel after she sits beside them. Mabel inquires as to why Candy has forks taped to her fingers. She demonstrates how she uses them to eat popcorn, and calls it an "Improvement of human being." Mabel then comments that she has "found [her] people." Later, when Pacifica Northwest arrives, Candy tells Mabel who the girl is, and she and Grenda cheer their new friend on in her competition against Pacifica. After Pacifica wins the contest by bribing Old Man McGucket, Candy and Grenda decide to stay and sleep over with Mabel, as opposed to going to Pacifica's after party like most of the other attendees. It is presumed that the trio spends the night dancing and reading magazines about boys.
Candy appears again in "Summerween," dressed as a peppermint for trick-or-treating; however, her and the others' motives change after the Summerween Trickster threatens to eat them if they fail to secure five hundred pieces of candy for him. Thus, she, Grenda, Mabel, Dipper, and Soos begin their trick-or-treating quest. At one point, after Dipper accidentally sends all their treats but the final one into a stream, the gang quickly races to prevent Old Man McGucket from blowing out the candle in his Jack-o'-melon to buy them more time, only to extinguish it with their sighs of relief. The Trickster shows up and prepares to eat them upon learning they have not met his request, but Soos drives straight through him with his truck and destroys the Trickster. However, he reassembles himself and chases the group into the Summerween Superstore. They try to escape by disguising themselves in various costumes in the store, and end up battling the monster after he eats Soos. Once they are saved by Soos eating the beast, they return to the Mystery Shack, where they enjoy candy, watch horror movies and celebrate pure evil.
In "Carpet Diem," Candy and Grenda go to Mabel's house to have a sleepover. Later, they find Dipper in Mabel's body and take him upstairs for a second sleepover. After Dipper and Mabel switch back, Mabel tells the girls about the carpet's magical properties, and Candy switches bodies with Dipper. Candy also switches bodies with several other people like Sheriff Blubs and Mabel. In the end, everyone ends up back in their own bodies.
In "Boyz Crazy," Candy, Mabel and Grenda attend a Sev'ral Timez concert. Afterwards, they sneak backstage, discovering that the band are actually clones being held as slaves by their manager. They release the boys and bring them to the Mystery Shack. Soon after, Mabel becomes highly possessive of them, forcing Candy and Grenda away. Eventually, Mabel decides to let the band go, and the three release them into the wild, in which Candy remarks they will probably not survive.
In "Gideon Rises," she and Grenda reappear as Dipper and Mabel prepare to leave Gravity Falls. The two girls are seen comforting each other. They do not appear after that, not even when the rest of the town gathers around the remains of the Gideon-bot at the end of the episode.
She appears in "Mabel's Guide to Fashion" though she is not seen while Mabel and Grenda do flash makeovers. At one point she and Mabel are shown scribbling on each other's faces.
In "Mabel's Guide to Colors" she participates in Mabel's survey of everyone's favorite colors. Later, when Mabel has declared a color emergency, she calls upon Candy, Grenda, and Dipper for ideas on how to make Stan see a rainbow. Candy quickly draws up a plan to reflect a rainbow from the falls into Stan's office window, and everyone agrees with it.She and Dipper stand in the back of Soos's truck and use a large mirror to reflect the rainbow into Stan's office window. Unfortunately, this creates a painfully intense rainbow-colored light beam that hurts Stan's eyes and also sets fire to some things in his office.
In "Scary-oke", she and Grenda enter the party. After Grenda smashes the "Stañatas" Candy picks up a few of the sweets or "Stan's brains" and puts them in her jacket. They dance during the music from Mabel's Boombox Sweater. Later she jumps into Grenda's "Get-away-pouch to escape from the "earthquake".
Candy is shy and insecure, largely due to being put down by popular girls like Pacifica, and for this reason tends to hang out with other girls that are rejected for being individuals. She enjoys spending time with her friends, whether the activity is going to a party, reading magazines about boys, having sleepovers, trick-or-treating, reading romance novels, or simply hanging out. She likes coming up with ways to innovate the human body, such as taping forks to her fingers in order to eat popcorn. Mabel describes her as very cheerful, and she expresses a humorous side. Even though she can be shy, she has a side of her that can be quite like Mabel herself. She is also shown to have a sense of quick-thinking ingenuity much like Dipper's, as she quickly comes up with a plan to help Stan see a rainbow. She expresses a love of photography, taking various pictures with her cell phone that she may post on the internet. She finds Waddles to be adorable, as seen in "Summerween," where during the credits, she takes pictures of him with Mabel and Grenda.
Candy has straight jet black hair (that sticks up in some places) and wears black glasses, and has most often been seen wearing a striped jade shirt, a skirt (which was dark green in "Double Dipper" but brown or purple at other times), white socks, black shoes, and a pink backpack. Along with this, she also has light pink blush spots on her cheeks like Mabel and wears black stud earrings. Candy also has a peppermint candy costume which she wore when she went trick-or-treating with her friends on Summerween.
- 107. "Double Dipper"
- 112. "Summerween"
- 116. "Carpet Diem"
- 117. "Boyz Crazy"
- 120. "Gideon Rises" (no lines)
- 201. "Scary-oke"
"Maybe we don't have as many friends as Pacifica, but we have each other, and that is pretty good, I think."
"I will make you internet famous."
"Candy falls down now."
"I'm a boy now! What up, bro? Let's grow some mustaches."
"I am so sweet, I could eat myself."
- It is likely that Candy is Korean because of the Hangul in the picture she took of the Summerween Trickster. However, "Chiu" is a family name of Chinese origin.
- Candy's last name is Chiu, which is most likely a joke, since Chiu is pronounced Chew. It could be taken to mean Candy Chew or Chew Candy.
- In the ComicCon 2013 panel Alex Hirsch stated that Candy Chiu and Grenda are Mabel's "life long friends."
- Her favorite color is "Magic Vision Poster".
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