Happened across the phrase 'Borderline Personality Disorder' and, thinking of my d-i-l's sister read it to her. Then discovered Histrionic Personality Disorder, read the symptoms and we found that fits sister better. Then we read Narcissistic Personality Disorder. Lo and behold, it fits my second oldest step-son to a T. Wow. Then I found a 'What's your personality disorder?' test.
And I took it.
Don't ever do that. You might not like the results.