it is often more obvious to the people who fall foul of the narc. in a family they tend to be the master manipulator who has all the power. they triangulate, they divide and rule, they identify a child as the 'golden' child who can do no wrong and who they can tend to be smothering of as an extension of them and the scapegoat child who gets all their bad stuff projected onto them. they don't allow their children to be people - as in 'whole little beings growing into their own selves' - they label them and decide who they are, what they do and why they do it and won't be shaken any evidence. for example if the scapegoat went onto to be an absolutely lovely, successful person it wouldn't change their view of them as deviant/bad/unloveable/etc it would just be that other people didn't know them like the narc did.
they create such weird dynamics that it is hard for the other members of the family to ever really communicate with each other properly and put together the pieces. the golden child and scapegoat are set against each other. it is often easier for the scapegoat to escape and see the narc for what they are as they at least have some distance whereas the golden child is so swamped by the narc parent it's hard to disentangle themselves and they may end up very bound to approval in their lives with their whole sense of self worth being based on being 'the good one', the one who is right, better etc. it's hard for them to individuate and go on to live their own life with their own values.
their rage isn't necessarily violent by the way - it can be like tantrums or causing scenes, sulking, acting like a child with a lot of power.
when it comes to children ime they can be very good with young children but struggle when they start to get their own personalities and deviate from what the narc has decided they are and therefore how they should behave, be etc. when they start to assert needs or ways of their own the narc starts to find them hard to handle and rather than just being able to allow them to be different or have character trait x it becomes about what is 'wrong' or 'difficult' about the child.
the narc i grew up with has never once said sorry for anything - even a small petty thing. she will not ever acknowledge being wrong even if it means being utterly ridiculous and defending something they've said that is clearly, patently untrue - that or they'll say i never said that with an utterly straight face that appears like they believe it and is mind boggling for the person on the other end of it.
when i was young i always thought there was some real her in there somewhere if i could just get it to it somehow. as i got older i realised this was false. there really isn't a normal person in there with vulnerabilities and deeper thoughts and something under the denial and lies. she reads till she falls asleep - with the light on - she cannot bear to be 'empty' for one second. in many ways she seems (now i'm older and more detached from how it used to effect me) massively emotionally immature and 'faulty' for want of a better word. she is not like other people and normal communication, appeals to compassion, appeals to logic, whatever do NOT WORK! you're not dealing with someone who fairly and rationally engages with you or reality.
sorry epic ramble.