Circus Baby was first seen in an opening cutscene, complimenting William Afton for the Funtimes state of the art technology. However, William was being questioned about some of the "design choices" made for the robots. These "design choices" are explained in the secret blueprints, which are very rare to trigger in the game itself.

Circus Baby is not fully seen in the game, only being "properly" seen in Night 5 in a decommissioned state. Through out the game, she is almost completely out of sight.

On Night 2, Circus Baby helps the player by telling them to not listen to Hand Unit's orders, as she knows that Ballora would kill the player if they followed orders.

On Night 3, going to the Circus Gallery and hiding under the desk will have her tell a story on how she used to be on stage at Circus Baby's Pizza World. In it, she explains that for some reason, she was focused on counting the number of children that would enter and leave the room. Nothing happened until there was one lone little girl, which caused Circus Baby to lock up and dispense ice cream. Baby couldn't move until the little girl stepped closer, then Baby heard screaming from her and the other children rushed in again, covering up the screaming. Baby couldn't remember what happened, but the secret minigame and the blueprints explain that Baby acted out on her programming and killed a child, who turned out to be William's daughter.

Starting on Night 4 is where things get odd. Circus Baby "kidnaps" Michael after getting attacked by Funtime Foxy, putting him inside a springlock suit from her old Pizzeria. On Night 5, she is seen completely gutted as she and the other Funtimes formed together to become Ennard. She then tricks Michael into entering the Scooping Room, letting Michael getting gutted and having Ennard escape from CBEaR's with him. Michael then slowly degrades, and Ennard leaves his body and hides in the sewers.

However, is the player were to enter the Private Room instead of the Scooping Room, it is revealed that Circus Baby is possessed by William's kid, as both of them utter nearly the same phrases in confusion and only wanting to escape from CBEaR's.

Circus Baby, joined as Ennard began to quarrel with the other Funtimes. They had enough of her being in complete control and ejected her from Ennard. This left Circus Baby to rebuild herself as Scrap Baby, who now acts as an independant animatronic.

For more information on Scrap Baby, click here or the image on the left.