Well, if Damien is one thing, he's not a narcissist.
His betrayal is based on the fact that he wants to pay for his mother's treatment.
By definition, characteristics of a narcissist are: self-centeredness, arrogant way of thinking, lack of empathy and need for admiration.
Now let's introduce ourselves to charity bowling: Damien is definitely unhappy in the situation. But the fact that he became Ryker's lackey in the first place is solely because he has to pay his mother's medical bills. Whether this is true or not should be easily proven by the sources of information the MC has through his contacts. What makes the story believable for me: Why should he keep up the story? Kenji never needed such a wild story either, so why Damien?
Ryker and Kenji, on the other hand, fit the definition of narcissist perfectly for me.
And to the gentlemen who want to screw Jasmine in front of Damien to spite him: If anything, do it right and get the phone number of Damien's mother and tell her what her son has done. Regardless of whether the story is true or not, I doubt very much that the lady will be very proud of him and you have hit him where it really hurts him.