Five Nights At Freddys 1, 2 and 3 Characters Guide!

Balloon boy

BB will not begin moving until Night 2. He starts in the Game Area and will eventually come to The Office via the Left Air Vent. With each of his movements, the player can hear him saying "Hello," "Hi," or simply giggling. BB will not show up on any cameras except the Game Area and the Left Air Vent, keeping his path of approach hidden.

Balloon Boy is the only animatronic that will not kill the player, but rather disable the lights (the Air Vent Lights and Flashlight) and is speculated to lure the other animatronics to The Office with his constant laughter. When the lights are disabled by Balloon Boy, the player is especially vulnerable to Foxy's attack, as he can no longer be stunned with the now disabled Flashlight. Putting the Head on while he is looking into The Office through the vent until the player hears him crawling back through the vents will prevent him from fully entering The Office.
However, the player should be advised that the banging noise might possibly be an animatronic besides Balloon Boy entering or exiting The Office or vents. After that, once Balloon Boy enters, his body will be fully visible, and nothing will make him leave, therefore jeopardizing the entire night (unless the player is close enough 6:00 AM or if Foxy never enters the hall, which may occur if Foxy's A.I. is set to 0 on the Custom Night).

He will not enter The Office if the player puts the Freddy Fazbear Head on while he is in the Left Air Vent's blind spot. If the player pulls up the Monitor while BB is in the Left Air Vent's blind spot, he enters The Office, laughing constantly. Once inside, he disables the Flashlight, as well as the Left and Right Air Vent's blind spot lights. This leaves the player susceptible to being attacked by Foxy, as well as being unable to check each vent's blind spot for other animatronics. Once inside The Office, BB will not leave until the night ends, should the player survive.