This Article Contains Spoilers - WARNING: This article contains major spoilers. If you do not wish to know vital information on plot / character elements in a story, you may not wish to read beyond this warning: We hold no responsibility for any negative effects these facts may have on your enjoyment of said media should you continue. That is all.
Chica the Chicken, not to be confused with her counterpart from the games, is an antagonist in the novel Five Nights at Freddy's: The Silver Eyes and a supporting character in its two sequels The Twisted Ones, The Fourth Closet, and in various stories of the Fazbear Frights series of short stories.
Chica the Chicken was one of the animatronics Henry Emily created. Charlie first saw her deactivated inside his dad's house, and she found her pretty scary. On July 1985, Susie was kidnapped by William Afton, dressed with a golden suit, who tells her he knows where her dog (who apparently died in a car incident some days prior) was, and asks her to follow him. The man then stuffed her into the suit.
Five Nights at Freddy's: The Silver Eyes
In 1995, after breaking inside the pizzeria, Charlie and her friends discovers that Chica and the other mascots were left behind. When they come back once again to the pizzeria, Chica, together with Freddy, Bonnie, and Foxy try to attack them, but she's stopped by Golden Freddy, possessed by Michael Brooks, a childhood friend of Charlie.
Five Nights at Freddy's: The Twisted Ones
In this novel it's revealed that, after the events of the first book, Chief Burker took the bodies out of the animatronics, damaging them in the process, and that he keeps them in the basement. After hearing that William Afton is still alive as Springtrap after being stuffed inside the SpringBonnie's suit, they reach the Twisted Animatronics, created by William to find and kill Charlie, and they starts to fight against them. During the battle, Chica and Bonnie defeat Twisted Bonnie.
Five Nights at Freddy's: The Fourth Closet
In this book, it's revealed that William Afton melted together the original animatronics' endoskeletons, including Bonnie's one, to create an animatronic known only as The Amalgamation, where he wants to transfer his consciousness to become definitively immortal. When Carlton Burker, who was injected with remnant, enters in the spiritual world, he meets a a young girl with blonde hair, called Susie, who possesses Chica. After William is pushed into a furnace by the funtime animatronics, who rebels against him, all the trapped souls are finally able to pass on.
Chica makes various appearences through the Fazbear Frights series.
Into the Pit
She appears in Into the Pit when Oswald travels back in time using a ballpit, coming back to 1985. Chica's one of the animatronics on stage, together with Bonnie and Freddy.
In Fetch, the protagonist Greg finds four deactivated adult-sized animatronics behind the show stage's curtains. Despite this has not be confirmed, it's possible they are the original Freddy, Bonnie, Chica and Foxy.
The New Kid
When Devon, Mick and Kelsey explore an abandoned Freddy's building, they find Chica deactivated on the stage, and various drawings of her on the walls.
One year after the missing children incident, Susie's soul is able to come back at her house to stay with her family, but each night, at 11:50 AM, Chica (that in this story seems to be a separate entity from Susie) comes back to take her again to the pizzeria. Those visits, however, will end when all the leaves will fall from the tree nearby her family's house. Susie, able to communicate trough drawings with her sister Samantha, wants her to find Gretchen, a doll the two fought over in the past. Susie hid it, but she doesn't remember where. During the last night, Chica comes back to the house as always, but, instead of standing on the entrance, the animatronic enters and starts to haunt Samantha, who, however, is able to find the doll in time, and give it to Susie. After the two sisters hug, Chica takes Susie's hands, and they disappear, with the spirit of the girl most likely moving on.
Chica shows an aggressive behavior towards adult people, thinking they are her killer. As a kid, she's very friendly and extrovert. She also seems to have problems remember things, forgetting she told her name to Carlton just a few seconds after she did that. In Coming Home, Susie is a sweet and sensitive girl, who likes reading stories, and seems to "antropomorphize" various objects, arriving to the point of naming a tree because she tought it was crying, and to think to dolls as real people.