12 Telltale Signs Of A Narcissistic Sister (This Is How She Behaves)

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Narcissists are among the most difficult people in the world to deal with because their need for narcissistic supply erases all semblance of rationality. Their lack of healthy identity mechanisms causes them to be hypervigilant and focused only on their own needs.

A narcissistic sister is no exception to the rule. Her behavior reflects her constant fear that someone will reveal her flawed true self. Of course, her siblings know her very well, and she possibly fears them the most. 

For this reason, a narcissistic sister will go to any extreme to be the center of attention. Additionally, she will blame her siblings for any failure on her part. She will also attack them and play the victim to win her parents’ sympathy. She can be vicious in her attacks and is rarely kind. 

It’s important to understand the behavior of a narcissistic sister because any narcissist in the family can cause significant disruption. In fact, it can literally tear the family apart. It can also do permanent damage to your relationship with other siblings.

When you know more about what she’s capable of doing, however, you can better combat her thoughtless self-absorption. Here is what you need to know about why she acts that way and how you can expect her to behave. 

Why Would Narcissism Develop in Only One Sibling?

Why Would Narcissism Develop in Only One Sibling

If you have a narcissistic sister, you might be wondering why you aren’t a narcissist. There are many reasons why two siblings in the same family could be so different. 

First, as researchers in the Insitute of Psychology at the Chinese Academy of Sciences have found, there is a genetic component to narcissism, particularly grandiosity and entitlement. That means it’s possible your sister received the genes that code for these narcissistic traits while you did not. 

That would make her more susceptible to developing narcissism, but it’s not the only reason she might be a narcissist while you are not. Another reason is that sometimes siblings are treated differently by their parents. 

This might mean that your parents were more lenient with your sister, or if they are abusive, they may have treated her differently than you for various dysfunctional reasons. Another factor that comes into play here is what may have happened in your early life as opposed to what happened in hers. 

For example, if she suffered some kind of separation from her parents in the first few years of life – perhaps she was in the hospital or something like that – she may have developed an anxious attachment style. If you never suffered that in your early life, you might have a more secure attachment style. 

Narcissists typically exhibit anxious or avoidant attachment styles, as researchers at the University of Wollongong in Australia point out. Finally, there simply may be individual personality differences that explain why she was more prone to develop narcissism while you did not. 

How Does a Narcissistic Sister Act?

Narcissism develops because a child comes to believe they are hopelessly flawed; that is their true nature. As a result, they are filled with shame and self-loathing, but that’s not a sustainable internal belief. 

The narcissist must bury that belief, that true self, and construct something better in its place. They build an elaborate false self-image, and they infuse that image with childlike notions of what it means to be good. They convince themselves they are perfect, superior, omniscient, and omnipotent. 

“Love doesn’t die a natural death. Love has to be killed, either by neglect or narcissism.”

Frank Salvato, Author

Unfortunately, that false self-image cannot sustain their fragile self-esteem. For that, they need other people to believe their delusion. So they learn early in life to manipulate others to give them the egoic support they desperately need. 

Everything the narcissist does is done to get a constant supply of adoration that will support their grandiose ideas of self. This is ultimately why your sister acts the way she does. It can cause you to feel confused and questioning if they even love you.

But the good news is, the following video holds the answers. Get a deeper understanding of your sister’s behavior and find out the truth about their love for you. Click play now!

The following traits are typical of a narcissistic sister and narcissists in general, and they all result from that fragile sense of self and internal shame and self-loathing.

1. Narcissistic Sisters Constantly Move the Goal Posts

Narcissistic Sisters Constantly Move the Goal Posts

Narcissists of all kinds also like to keep everyone around them off-balance. People are easier to manipulate if they don’t know what the goal is and when it might change. 

Your narcissistic sister may tell you one day that she doesn’t want to be involved in an activity you’re planning, and the next day, she will accuse you of not loving her because you didn’t invite her to that very activity. 

Anything you say in response, she will reply with venomous accusations about how you have never really cared about her needs. Again, there’s no winning here. It’s impossible when you don’t even know how winning is even defined. 

This is your narcissistic sister looking for any reason to be offended, to be the victim of your bad behavior. She wants to make it look like you’re the one who has mistreated her

I have a friend with a narcissistic sister who recently called their father to complain about how her sister was treating her. She was yelling so loudly that her sister could hear her both physically in the house (the narcissistic sister was in the basement) and over the phone. 

My friend got angry and yelled back at her, telling her that she was wrong and was acting crazy. Her narcissistic sister then proceeded to rage into the wee hours of the morning. She was yelling out things to herself but loudly enough so her sister could hear, of course. 

The next day she told her father that she couldn’t help with a chore because she was so exhausted. She said, “I was wound up last night after being yelled at and couldn’t sleep.” Her father noted that she had started the argument and that she was yelling as well. There’s no winning with a narcissist.

2. She Has No Empathy

Like all narcissists, your narcissistic sister has no empathy. Empathy requires that she be able to put herself in someone else’s position to understand how they feel. 

“Narcissists tend to have a diminished sense of empathy, meaning that it is difficult for them to attend and relate to the thoughts, feelings, and suffering of others.”

Sander van der Linden, Ph.D., and Social Psychologist at the University of Cambridge 

But a narcissist sees everyone else as an extension of their own identity. Therefore, there’s no reason to put themselves in someone else’s position because that person is automatically in the narcissist’s position. That’s all they should be concerned about – the narcissist. 

Moreover, a narcissist can’t be empathetic to themselves. That self-loathing and shame keep them from treating themselves in a tender manner, so how can they possibly treat someone else with kindness? 

Without empathy, she can’t understand the effect her behavior has on you or anyone else in your family. This is part of why a narcissist can be so cruel.

3. She is Entitled to the Extreme

Narcissists don’t just want to be treated well and given things they need and desire; they feel entitled to that kind of treatment. They believe it is the duty of everyone around them to give them what they want when they want it. 

In the narcissist’s mind, they are entitled to special treatment, and you are not. You have no right to anything you get, but your narcissistic sister does. 

She expects people to treat her with kindness but does not return the favor. She expects her needs to be met but does not meet anyone else’s needs. 

She is a taker, and she will never be a giver. She will rant and rave about her rights while denying other people the very same rights she claims she has. Moreover, she will not see the hypocrisy in that behavior.

4. Gaslighting is the Default Behavior

Gaslighting is the Default Behavior

Like all narcissists, one of the most insidious weapons in your narcissistic sister’s arsenal is gaslighting. That dress may be black, but she will do her best to convince you it’s white. 

She will distort reality until it no longer resembles any kind of logic. She will make outrageous claims, and if you contradict her, she will question your memory and even your sanity. She will insist that your memory is faulty or that your interpretation is questionable. 

That’s the goal, to get you to think there’s something wrong with your version of reality. She wants you to rely on her interpretation so she can manipulate you at will

Gaslighting Phrases Your Narcissistic Sister May Use
  • Do you not remember that? 
  • We have the same conversation every time we talk about this!
  • Are you losing your memory? 
  • That never happened. 
  • I never said that. 
  • That was only a joke. 
  • You’re too sensitive. 
  • I can’t believe that’s what you think happened. 
  • I already told you that!

5. She Shape-Shifts at Will

You will find it difficult to believe how many masks your narcissistic sister will wear. She will shape-shift her identity at will to be whoever she needs to be in order to manipulate the people around her. 

She can be a completely different person to your brother than she is to you. That way, the two of you won’t be able to work against her. In fact, it seems like the two of you know two completely different sisters. 

This is also a form of gaslighting because she’s changing her personality to create an illusion. She wants different people to see a different person when they look at her. That puts her in control and makes it easier for her to manipulate the situation

This kind of tactic drives a wedge between you and other family members or friends. It also gives your toxic sister the ability to control the people in your life who may be most important to you. It’s a way to isolate you so that you will always need her.

6. She Triangulates All Familial Relationships

She Triangulates All Familial Relationships

Triangulation is effectively playing both ends against the middle. A narcissist in the family will tell one person one thing and another person something entirely different. It creates confusion and chaos, and the narcissist loves it. 

Your narcissistic sister loves drama, and she feels powerful when she can successfully manipulate people and situations. She can manage to sow such disruption that she can, in fact, tear the family apart. 

She has no compunction about lying and gaslighting, so she will make outrageous claims just to get a reaction. If you’re not constantly on guard for this kind of manipulation, it can destroy close family relationships. 

Being able to do so makes your narcissistic sister feel powerful. She has the ability to make things happen and make people do what she wants. It makes her feel superior to others and gives her a feeling of control.

7. Narcissistic Sisters Monopolize Every Conversation

If you’re hoping to get a word in edgewise in a conversation with your narcissistic sister, you shouldn’t hold your breath. Your toxic sister can prattle on without seeming to take a breath for exceptionally long periods of time. 

She will go on and on about the smallest thing. She doesn’t care whether it’s boring or if you have something to say. She only cares that you’re focused on what she’s saying. She has your attention, and she is loath to let it go. 

Additionally, she loves being in control of the conversation. She doesn’t want to really hear about what you have to say. She doesn’t even want to know how your life is going. She expects you to care only about how her life is going. 

Interrupt her, and you’ll be facing an accusation of being self-absorbed or not caring about what’s going on with her. She also believes she is showing concern for you just by talking to you. That should satisfy you that she cares about you. After all, she is telling you about herself. 

Narcissists just can’t focus on other people, not even when it means acting politely. They often refuse to show those kinds of manners because they believe themselves to be above any rules. They also have a tendency to bring any conversation back to something about them. 

You might be trying to tell them about something that’s happening to you, but suddenly you find you’re talking about either how that affects your narcissistic sister or how she has it even worse or better.

8. She Constantly Belittles and Accuses Everyone

She Constantly Belittles and Accuses Everyone

A conversation with a narcissist is laced with venomous accusations and constant belittling. Your narcissistic sister will start most every sentence with an insult. The following presents some examples of how she might word things in an insulting way: 

  • I know you don’t care about this, but it’s important to me…
  • I realize you’re angry about this, but you should know…
  • I know I’ve told you this before, but I guess I need to tell you again…
  • I’m sure you find this unimportant, but I think you should know about it.
  • I know you’ve called me rude for saying this, but I think it’s true.
  • You’re more of a thinker, so you don’t empathize with this, but as a feeler, I…
  • You can’t understand this, but I do, and it’s important. 
  • You don’t like this person, but she’s my friend, and I care about what happens to her.
  • It seems like no one really cares about what I think, but I have to say…
  • We’ve had this conversation several times before, but I guess we have to have it again…
  • You can’t seem to understand no matter how many times I tell you…

As you can see by these examples, your narcissistic sister starts every conversation with something that is a not-so-hidden jab at you. Either you can’t understand or don’t want to, or you don’t listen to her. 

She starts her conversations with assumptions about how you feel or think, and it’s always something negative. Typically, the conversation only gets worse from there.

9. She Will Betray Family Members Anytime it Benefits Her

Narcissists have no loyalty to family members, you can learn about in the following in-depth video. They think in binary terms, and either you’re with her, or you’re against her. If you’re against her, you’re an enemy that needs to be crushed. 

Even if you’re with her, if it benefits her to throw you under the bus, she will do it in a New York second. She is only concerned about her own image, and she expects that you should understand that. 

It’s not unusual for a narcissist to blame you for something one minute and turn around and treat you as if nothing had happened the next. They don’t understand your needs or have empathy for your situation. Your narcissistic sister will not hesitate to do that to save herself from any kind of embarrassment.

10. She Will Smear You

If you refuse to play along with your narcissistic sister’s antics, you will become the enemy. If she can’t control or manipulate you, she will mount a smear campaign against you. She wants to be sure that other family members see you as the villain. 

She has no problem lying to make sure that your loved ones believe her and not you, either. She will spread rumors and lies to your family, your friends, and depending on the circumstances, even coworkers. 

When you become the enemy of a narcissist, they don’t just want to prove you wrong, they want to destroy you. They will go to extreme lengths to make that happen. It’s a very toxic situation that puts you in an awkward position. 

It can be difficult to defend yourself because you sound like you’re the one with the problem. She puts you on the defensive in a way that makes it difficult to rebut her accusations. 

It is sometimes to better to allow people to simply come to their own conclusions over time. Your real friends are allies are unlikely to believe her in any case.

11. She Will Turn on the Charm to Convince Others of Her Story

She Will Turn on the Charm to Convince Others of Her Story

Your narcissistic sister is not without her charms. She can turn it on when the situation calls for it. Narcissists can be extremely charming when they need to be, so don’t disregard this as something you don’t need to worry about. 

My friend’s narcissistic sister can really be charming and seem so caring when it suits her to act that way. She can’t hold it together for very long, however, and that is typical of narcissists. 

They can turn on the charm for a while, but it won’t last for long. Her sister has managed to be charming for as long as six weeks, but then the pressure starts mounting, and she eventually blows. 

“Nobody can be kinder than the narcissist while you react to life on his terms.”

Elizabeth Bowen, Author

This is typical of many narcissists. In fact, people who are the romantic partners of narcissists often feel as though they have met their soulmate in the initial stages of the relationship. It’s only later that they realize they’ve met the devil in disguise. 

This is something you need to be aware of because she will be charming to convince others that you’re the villain in your relationship with her. If she is in contact with the people she’s trying to convince for very long, they will eventually see the truth.

12. She Competes with Jealous Disregard for Anyone Else

You’ve probably also noticed that your narcissistic sister is extremely competitive. She’s jealous of anyone else who is in the spotlight. When you’re getting attention for some reason, she will find a way to steal the limelight away. 

My friend’s sister even resorted to faking various physical ailments to get the attention back on her during times when my friend was in the spotlight. She managed to disrupt graduation parties and other such celebrations when my friend was in the limelight. 

A narcissist’s jealousy knows no boundaries, and she often competes desperately for attention. She needs it to prop up her false self-image. It’s sad, really, but it’s also very disruptive. 

Final Thoughts

Any narcissistic family member is a disruptive force in the family, and a narcissistic sister is no exception. She has many tricks up her sleeve to manipulate and control other family members, and she can be so disruptive that she can tear the family apart. Because she knows you so well, she also knows just exactly what buttons to push to get a reaction out of you. She knows your emotional triggers. 

That’s why you need a way to combat that kind of manipulation, and I have a method that can you help you do just that. I have created a 5-Step Roadmap to Heal Emotional Triggers that helps you identify, defuse, and even heal your emotional triggers so your narcissistic sister can never use them against you again.

To get a free copy of this handy guide, just click here and I’ll send it straight to your inbox. Get instant access to this handy guide by clicking here! You’ll receive this comprehensive guide straight to your inbox, so you can start reading and taking action today.


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Narcissistic abuse takes a terrible toll on your life. I’m Patricia, and my mother is a narcissist, so I know what you’re going through. These blog posts will help you understand narcissism better and give you tips for dealing with the narcissists in your life. Healing starts here!

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