I have seen this in my own life a few times and I noted that with my wife when it seemed that it was her and I  against the world we got on very well.
To feel that we are side by side with someone or a group against a known foe it brings forth a camaraderie a mutual trust and strong bonding friendship, is to feel that we are all as one, and we will defeat this foe etc.

People feel safe and stronger in numbers, more powerful, more able, and it is a nice comforting feeling to know that many have us protected and are looking out for us.

Manipulators know this and they use this to bring a person under their control, especially if the victim is afraid, suffering mentally, is anxious, and the fears are used to bring that person under their wing for so-called protection. love, help,
comfort, etc. people who are in fear are anxious for safety, so when it is offered they run to it, accept the love (faked or not) and gratefully hang out with the group.
But in doing so they become indoctrinated with the thoughts and beliefs of that group. and once trust and faith are established then the victim will accept what he or she is told and will in time become one of them.

Creating a fake fear causes insecurity and one steps into survival mode seeking help, shelter and a safe haven,  and the manipulator will offer it and those who back up and support the manipulator fill the parts of the protectors, of
the worthy, hope and safety.

Once in the Safe Haven the manipulator/s can form the mind of the victim because hope, faith and trust have been established between the victim and the manipulator/s.
Flying Monkeys make excellent manipulators without even knowing it, as they are told only certain things and in their desire to see right conquer wrong they will do what is necessary to “help” the victim, in other words doing what the
Narcissist/Manipulators suggest.