Bitch
This term is a persecutor subtype.
A bitch is a headmate who is comfortable being a bitch to people inside or outside the system who deserve it. This can count as a type of protector or persecutor depending on the context of the situation, but the main discriminator is that a bitch will not hold back on whoever they are protecting the system from.
For example, if someone is being rude to the system in a way they don't deserve, or has consistently made their life harder, then a bitch will tell off the instigator in an unfiltered and blunt way.