The Companion Pony, otherwise referred to as COMPony, is a pony who was engineered based on the design of a Companion Cube and programed with the same technogoly as turrets (though hers was significantly modified).
Living in an apartment in an undisclosed city, COMPony lives with a scientist by the name of Suzanne; a woman who works for Aperture Sciences and manufactered her with her knowledge of their functioning products and software.
Due to the type of software she runs on, she's required to download updates from the internet, similarly to how a computer would. Though, unlike a computer, when a virus enters her system it becomes rather obvious and her personality can change entirely in a matter of hours. One particular instance left her quite wanton and welcoming, though she recovered in a few days once the program was deleted by Suzanne.
And, with technically no gender, COMPony actually has certain accessories that can be attatched to her body and influence her gender.