Update: I want to further clarify this answer. Every problem in life we have, is due to our unawareness of the truth of life to a degree and our resistance to becoming aware of it. When we are truly aware of our situation and inner reality, we don’t experience a perception of a problem. We are already in tune with life as it is.
When in your case, if to be in the good side of your boss means that you ignore seeing things as they are and try to please your boss by submitting to his ego’s desires, then his ego will be heavily influencing how you direct your life energy to create your experience. This is like submitting to a leader that you don’t respect despite your heart’s indicating that this is not for your highest good. This will create more of the same ego in the environment, because now your energy too is being used for this purpose. So, you will be building within yourself more of his ego and his ego will be influencing your reality more now, whether you are with him or not, even after you leave the job, because you have invested more energy to it. This will go on until you face and become aware of the truths that you were running away from when you chose to submit to his ego ignoring your heart. That is why, it is of utmost importance that we start facing reality moment to moment with awareness, and this way we will be in the good side of truth, not avoiding it. Then, we can naturally act with greater wisdom because now we know better, in virtue of not having avoided/not avoiding truth.
Usually a big problem while dealing with narcissistic people is not being able to accept them as they are and trying to change/manipulate them with an unrealistic hope arising from not looking at our relationship honestly and deep enough. This naivety can lead us to be used by the narcissistic person again and again. We must catch ourselves in this pattern and responsibly deal with the person using us as early as possible. So keep your eyes open to life, live in awareness, and with a pure intention, honoring the knowing of your heart. If you choose to confront them, do this from a place of unconditional love. Honestly, courageously state your boundaries without judging them. Stop empowering their hold on you by as consistently as possible honoring your deepest inner truth above all else and its weight on your reality will keep lessening. This way you will also be showing the narcissistic person that their ego is powerless vs the power of spirit. When you succeed in changing yourself, the change will also spread into the world. He won’t be able to forget the memory of seeing the strength of your spirit. It will be a positive influence for him as well, a seed he can benefit from when he chooses to start facing reality more.