A Narcissist is watching for what makes you laugh, when do you cry, what excites you, where you show fear. Basically what brings you up and what takes you down.
They listen, watch and learn.
Most of them can size up a new target within minutes. They watch how you carry yourself, are you confident in some settings, fearful in others, and what makes you tick.
They are looking for your hot spots, and weaknesses in order to gain control of you, your emotions, and they are looking for what specifically they may gain from you. Where you are vulnerable and what you have to give to them.
The process is two fold for the Narcissist, what am I going to take and get out of the deal and where is my access?
They will also be looking at your strengths, what is in it for me? They want the best possible supply they can secure, yet they want to be in control.
The Narcissist is looking for what they want and need.
This will vary as to what it is they want from you.
They want the best they can find for what ever those needs may be.
Sex in general
Financial security/Cash Cow
Attractiveness to make them look good in your presence
A victim to tolerate covert and overt abuse
A Mother for their children
And so on….
Obviously all these will not apply to you. You are selected to serve your particular purpose.