Is Their "Ex" The Narcissist, Or Are They?

One way to tell if a person might actually the Narcissist, or if they're telling the truth about being the "victim" of their past relationships with alleged abusers or crazies:

How are their exes doing (or ex-friends or family members)?
Do their exes seem like they're recovering from some kind of traumatic time in their life, or are they doing pretty well, even quite well?

How many of their exes are doing well, compared to how many are not, who appear to be having a hard time of it?

Narcissists use the resources of whoever they attach themselves to, or whoever they happen to be attached to because of family or work or community relationships.
They don't support another person who is in any kind of need (unless they're pretending to in order to gain their trust and get closer to them.)
They don't support the other person, even though the person is supportive toward them, so the other person often ends up becoming very depleted in most or all ways (emotionally, spiritually, financially, mentally, etc.)
They often destroy or take away the means of self-support a person had.
They also take away the person's support network if they can (friends and family), if the people around them are easily influenced. Many people are, and will turn on a person quite easily if they're led in that direction.
Because they are typically abusive in many ways, they often leave deep scars on a person who they were connected to in relationship, and the closer the relationship (the more the person trusted them), the deeper the impact.

So the target of a Narcissist often ends up in a much worse position than they were before the met them, and can end up with a lack of "friends" who were apparently superficial in the first place, or they would still be around, especially when the person went through such trauma. 

Since Narcissists only take but don't give, they often end up in better positions, and often continue to gain and gain throughout their lives. They also tend to be good at cultivating and maintaining superficial "friendships" that don't require any genuine, real-life-mutual support like one would need to give in a healthy friendship, family or romantic relationship, so they often appear to be surrounded by good relationships.