Around 2007, I worked at a retail store, and had what I would say was a very educational experience working with whom I believe to be a narcissistic coworker. I'll call this former coworker "S". I worked at the store for about seven months, and during that time, I did get along with S, up until the last month or so of my employment there. On the surface, S was extroverted and outgoing and always had a smile ready for others. If she was in the break room and another coworker came in, S would mostly be the one to initiate conversation. I noticed that she got along with most of the floor employees, and also managerial staff. Having said all of that, I had an inkling that S was a covert bully who desired control and attention. I realized that her love of conversation and laughter really meant that she could be at the center of attention, and she wouldn't hesitate to interrupt the conversations of coworkers even though those conversations had nothing to do with her. She never once thought it was rude to just interrupt. She also had a habit of inquiring to coworkers about what their conversations had been about and also inquiring about issues that coworkers had with customers. If she noticed that a transaction was taking a long time, immediately after the transaction, she would be the first one to ask "What happened with that customer?" At first, I thought that she was just extremely nosy, which she was, but upon further observation and reflection of her behavior, I realized that she was a purposeful information gatherer and that she had an excellent memory. I watched her in action with coworkers a few times, and also realized that she was doing the same things to me. There were times that she would ask me a question pertaining to my work or other matters, and then the next thing I knew, I would overhear her repeating my words back to managerial staff or any coworker who happened to be nearby. I don't believe that part of her behavior was exactly malicious, but it did show that she lacked boundaries and could not be trusted to keep information (even trivial information) to herself. In addition, S also had a way of being passive aggressive and making subtle remarks about my competence and work ethic. She would make these comments in a tone that would suggest that she was just joking and being friendly, but I still did not feel comfortable with her comments and digs at my expense because when she engaged in that behavior, I felt undervalued as an employee.
I now recognize S's behavioral tendencies as having to do with a LACK of EMPATHY on her part, because at the time that I worked with her, I also noticed that she was quite firm about protecting her own space and boundaries. She would be the first one to tell someone else NOT to do something as soon as she felt like her threshold of tolerance was crossed. If she felt bossed around or pressured or that someone was being unnecessarily rude, she wouldn't hesitate to confront; however, if she was engaging in those behaviors toward someone else and was confronted, she would have contempt for the person confronting her. If not contemptuous, then she would act like she was in the dark and unclear about the problem and that it was the other person's responsibility to clear it up and express their preferences, while she would just stare at the person while they made their case to her.
I didn't put all of this together, until after a few revealing conversations I had with S. I really believe that Ns end up telling on themselves a lot. In one conversation, S referred to another coworker as a "bitch" and when I asked why she didn't like that coworker, she explained that that coworker had confronted her for being bossy and also told her "Do not tell me what to do". The fact that this coworker had told S to butt out, really wounded S's ego, and she couldn't handle it. In another conversation that S and I had while we were sitting in the break room, S told me that she had once confronted a shift manager in the store manager's office, because she felt like he had been pressuring her to complete tasks in which she thought was an unreasonable time frame. Regarding this same shift manager, S told me that she had once referred to him as a "dog barking" directly to his face. I couldn't believe that she would have the nerve to say such a thing directly to a shift manager, but she indeed had the nerve and made no apologies for it, either. If I or another coworker had ever dared to make such a disrespectful remark to her, my or their tongues probably would have been cut out of our mouths. Months after those informative conversations and my own observations and feeling of uncomfortableness with S, I began to put two and two together and realized that interactions with S were one sided in her favor. While she did not have compassion for others, she expected people to understand her perspective and treat her with respect. Once I realized this, my dislike for S was firmly established because I saw her as being a consummate taker with no ability to truly give or humble herself in interactions with others, while feeling fully entitled to those pro-social behaviors from others.