Story time!
My brother (3 years younger) suffers from pretty much the same global disorder as described in the blog; the main difference is that we're in France (well, my family still is; I moved a few years ago).
Throughout childhood, he presented a mix of pretty much every single psychological disorder possible- bipolar, paranoia, kleptomania, depression, etc. He was extremely manipulative, and knew how to be perfectly sweet like the author describes. I always saw it as a very contrived act on his part, one in perhaps in lost himself at times- but I believe that when he presents this adorable facade, he is mostly in control of it. He has definitely threatened my parents or myself with a knife, and I'm glad we have decent gun control in France. I believe that if he hadn't grown up in a wealthy privileged environment, he'd be dead or roaming the streets today.
IQ tests put him in the ~120-130 range, and psychologists recommended a wide array of solutions, ranging from the behavioral (for example one determined that it was because he didn't feel secure and had enough privacy, and suggested that he should get locks for his room etc.- that led to an entire different set of complications, and that psychologist was abandoned promptly.) to the medical (although he was never subjected to the wide variety of antidepressants cited in the article- France in the 90s-early 00s seemed to avoid those sort of things).
Ultimately, nothing worked. Things got much, much worse with adolescence; he went to 4 schools, all very different (one public school, one catholic private school, one boarding school in the countryside, etc.), and got kicked out of all of them but one. My parents did find a few things that mitigated his conditions: for example, he was in the boy scouts for a few years, which helped.
Today he's 20, barely graduated high school; he now lives somewhere in the French mountains with his girlfriend, chopping wood and harvesting grapes. We haven't talked (other than "hey what's up" at family meals once a year) in 7 years or so.
I could probably write an entire book on the topic, but would rather avoid to do so for the moment; but if anyone has questions, I'll gladly answer them.