How do you keep a narcissit interested in you?

Seriously, why would you want to do that?  If my understanding is correct, a narcissist is preoccupied by self-admiration.  An almost completely self-centered person, so to speak.  You will never mean very much, if anything, to a person with that type of personality, and quite likely, you will be miserable due to your association with this narcissist.  Your best course would be to look for someone else who will share their life with you.

  this question has me laughing out loud Sweetie!    The answer is:  You cannot....no way...no how....while he/she is busy looking at themselves in the nearest reflective glass.....run the other way....

Make sure you let them be the center of attention all the time.

keep holding a mirror up so he can see himself

Wear mirrored sunglasses any time you are with them.  Talk about them constantly.  Compliment them constantly.  Tell them how wonderful they are and how lucky you are to share the same air they breathe.  Talk about how they are the very best at everything they do...best parent, best looking, most giving, etc.  And whatever you do, don't forget to tell them that they are always right and the rest of the world has mistreated them is some terrible way.    That should do it.

Cute answer from Jada.  Sounds like you might know one or two.

Lol Will D...just one!