You might want to call someone subversive if they are sneakily trying to undermine something, from the social structure of your high school to an entire system of government.
You can use subversive as a noun or an adjective without changing it one whit. Note the prefix sub meaning "underneath" with the remainder coming from the Latin vertere "to turn." Think about a subversive as a sneaky kind of revolutionary who tries to turn the system from underneath. Art or literature is considered subversive if it attempts to undermine the morals and traditions of a society.