Description and behavior
An imposter spy is not particularly a friendly, but it is friendly enough to make it here. Imposter spies tend to wear the Handsome Devil, but otherwise no specific loadout is needed, except that they will only use the stock knife and disguise kit. What separates an imposter spy from a regular spy is that they will disguise themselves as other friendly players, such as a Hoovy or Spycrab, only to backstab other friendlies.
They will not usually capture objectives or push the payload. It seems that their only goal in life is to backstab (in the truest sense of the word) friendlies. The reason they only use the knife is because they haven't yet figured out that they posses a revolver. The ones that do progress from this stage and become the spy main.