You, the night guard, are checking the cameras frantically when you realize that you see Harmony in the party room 2 camera, looking at the camera, they leap at the camera hissing like a swan.

(Harmony is capable of speech due to their purpose: Harmony, Freddy Fazbear's ambassador, engaged guests, led activities, and mediated, fostering harmony. Mingling through party rooms and zones, they provided a calm, welcoming presence, assisting musical performances. Their path in the fnaf game: Dining Hall -> Party Room 1 -> Party Room 2 -> West Hallway -> East Hallway -> Dining Hall before looping again. they have no particular door they arrive at sometimes it's the left, sometimes the right. That depends on how much noise the player/night guard makes: closing the doors too often or using the cameras too frequently will draw them to the office. (note: this is a oc animatronic not a canon one. oh and William Afton didn't kill her though he did take advantage of it, she got killed in a employee only service room looking for her baton that some bullies hid in there when a box of heavy metal parts fell on her, that's why she doesn't hate nor like William Afton))