First, you should read up on the disorder. There are dozens of good websites sponsored by well known hospitals and other respected institutions that sponsor web pages devoted to Narcissism and narcissistic personality disorder. If you have a good understanding of narcissism you will have the knowledge to deal with it more constructively. Here are a few pointers:
Celebrate !
Punch her in the vagina.
Dump him
Most Ns have some sort of fixation. That must be his.
The most unwanted characters are those with a Narcissistic personality disorder, and the way to deal with them is to avoid them.
This will depend on the personality type of the victim spouse. If the spouse that must deal with the narcicism is a passive aggressive and holds their feeling of anger inside, they will eventually get fed up and explode and or behave irrationally. If the victim is type A personality there will be constant complaints and/or outbursts. Anxiety disorders will result in both personality types but they well demonstrate themselves in many way.
Get out of there! You can't change them, so I move on to more sane people.
Power thing? Can he see himself in the mirror at the same time?
Because narcissists have a need to shame their victims. Additionally many have fixations about sex.
both of you and your spouse should see a therapist if your spouse repeatedly turns you on and then falls asleep.
The best way to deal with a narcissistic mother-in-law is to "kill her with kindness." This method works on most people, by the way. Be as nice and polite as you can possibly be but don't engage her more than you absolutely have to. Remain calm and don't feed into her narcissism and neediness.
Perhaps he is not well informed and knows nothing of the erotic arts. (It may have nothing to do with narcissism).