Aggressive Or Defensive

People who have aggressive behaviors, especially if they suffer from some form of illness or disorder (can include PTSD) often do NOT seem to know the differences between aggression and defense, or the difference between domination and expressing one's own point of view.
They also don't seem to know the difference between slander and seeking help, advice, or solace. (Whether they're on the talking end or the receiving end.)

The "aggressor" is the one who is "chasing" a person to "make them" give some kind of response, "make them" give attention, or "prove" to them that they're "wrong".

Aggressors also commonly actively try to RECRUIT OTHERS for their "side" against a person.
Aggressors actively do things TO another person, and ABOUT another person, without respect for the person.
Aggressors often try to MAKE other people feel, do, believe, and say what they want them to.

A POST on Facebook expressing one's own feelings, observations, or point of view is PASSIVE and non-hostile, unless it mentions a specific person; then it's aggressive.

A countering COMMENT on someone else's Post is aggressive, not passive. An insulting comment is hostile, not defensive.

Messaging someone with accusations, name-calling, demands, or threats is aggressive, and hostile, not passive.

Going TO another person and trying to get them to DISLIKE and TURN AGAINST someone they know is aggressive, very hostile, and manipulative.

Using a dog for an example, the dog who is walking around out in the street looking to bite a person who's also walking in the street, because they're there, or because of their smell or their shoes, is AGGRESSIVE. The dog is INITIATING contact with the person, the dog is actively going TO THE PERSON in order to bite them.

But if that same dog is in a yard, behind a fence, and a human person comes to the fence and taunts the dog, and reaches over the fence, then that dog is DEFENDING him or herself. The HUMAN in this case is being AGGRESSIVE.
There's no justification for it, the human initiated contact and invaded the dog's space.