If you actually examine the narcissist’s narrative, you quickly notice that they are full of crap.
For instance if you examine a narcissistic parent who tells others how you hurt them and say mean things, you quickly notice that they are the one who constantly demeans, disrespects, and manipulates the adult-child. And when the child becomes more assertive and stops giving them resources (time, money, attention), they see it as aggression because they feel entitled to those resources.
If you examine further, you notice that not only the narcissistic parent was initially disrespecting the adult-child’s boundaries, but is also retaliating further now by manipulating others into siding with them.
The same is the case in professional environments or personal relationships. The narcissistic party does something toxic, the aggrieved party reacts and stops the perpetrator or distances from them, and then the narcissist retaliates by trying to shape the social opinion into a narrative where they are the good, righteous party. Sometimes they even convince others to bully and intimidate the victim further.