We all grow up from childhood to adulthood. We all play a certain role in the family. And the truth-teller is one such role especially in a family system with narcissistic parents. Usually, there's one child who sees everything whether they tell it or not. As kids, they'd say it, often from a naive perspective, like "Mom doesn't like it when others don't think she's smart". It's all about simply telling the truth.
Bless their hearts!
The danger and the challenge are that narcissistic parents don't like it when others call them out. And the child may eventually come to understand that before long and then keep the truth to themselves.
Because, by the dint of telling the truth, the child runs the risk of getting scapegoated really fast. And of becoming the proverbial black sheep. This is the reality in the family dynamics where the parents are abusive and narcissistic.
It is usually the case that the truth-teller child sees things with clarity more than anybody else. Although they may not know the word narcissist, they know something isn't right. The triangulation, the gaslighting, the co-dependency, the trauma-bonding. They know these aren't OK. Even without knowing any of the vocabularies.
They tend to have a rich inner world. They may have a fantasy about finding a chance to escape from the dysfunctional system. When they're old enough, they may figure out a way to safety and sanity. Joining the military or taking a teaching position somewhere, some of those things. Trying to maintain a distance from the source of pain. Or it could even be an all or nothing.
Their struggles may go unnoticed by others: the impact of the narcissistic family system can follow the truth-teller from childhood to adulthood or other adult relationships; resilient or not, anxiety plays a big part in their life; and some would isolate themselves socially as they take the proverbial " psychological punch".
At an early age, the truth-teller child grasps the reality that the significant players in their life, the people who're supposed to keep them safe and love them unconditionally, didn't care. And that recognition is painful. The more one can understand that the more one can crack, break, open out of it.