Passive-aggressive behaviour damages the relationship with the individual one is in conflict with, as well as others who are inadvertently drawn into the conflict situation.
This style has the appearance of a passive or compliant individual on the surface, while acting out their anger in a subtle, indirect or behind-the-scene manner. People who use this style often feel as though they have no power, are stuck, or are resentful and fearful of addressing the conflict with the other.
A very common form of passive-aggressive behaviour is gossip. They may be all smiles and charm to you, while setting up booby traps alla round you.