All narcissists are delusional. They have a delusional view of themselves and a pathological self involvement. Sociopaths will mirror this delusion (manipulating the emotionally mentally ill is one of their highest skills) and they will make the narcissist feel the self involvement is normal.
Narcissism is actually a confusing term, there are at least three pathological types that I know of: garden variety, malignant and rigid. Rigid is the one I am most familiar with — the narcissism of Scott Peck’s People of the Lie, aka, the perfect, the mentally ill evil. They have zero consideration for anyone else, their whole psychic universe is organized around protecting their perfectness. This is why they give up the lived life, they gain total perfection.
The rest of us go through life with daggers of defeats, failures and regrets attached to our backs that tweak us now and then, because we have consciences. Narcissists know none of this, never having made a mistake in their lives, leading a life absolutely without error (as long as they can maintain the fiction). But the maintenance of this false world is exhausting, turning to sociopaths for enabling must be such a relief.
They are so lacking in empathy that they are often mistaken for sociopaths themselves, I term them one of the faux sociopathic states. Joining with a sociopath mirrors their vast selfishness and disregard of others. They often pair off with sociopaths to form an evil couple.
Furthermore, there is a phenomenon known as narcissistic catastrophe (at least for the malignant and rigid types). The catastrophe occurs when the edifice of the false self is overwhelmed by reality, when the betrayal of their own soul is overwhelmed by their own soul needs. At that point they are lost at sea, unable to recognize friend from foe, in personality meltdown, they probably feel they don’t even know themselves — permanent psychotic dissociation is an extreme danger.
At this point they need protection both from themselves and from sociopaths (for whom they are now like an artist’s palette). I actually knew a rigidly narcissistic therapist to throw such a client to sociopathic manipulators. Narcissism is that evil, almost like a personality virus that won’t allow anyone under their influence (even their own child or client) to escape narcissism to live a lived life, a soul life.