I'm imagining the horrible little blighter is now totally civilised and you and your wife, Patrick, congratulate each other in having survived.
My daughter's best friend from high school was the perfect child in a family of seven.
Believe me, there is no perfect child. Instead I venture to suggest she was a child who bottled things up, found no avenue to express her emotions, and when that wire came to trip her/him up, the reserves and experiences simply weren't there.
Tell me Patrick, reassure me that your devil in disguise, you highly-intelligent protege, is lovable beyond measure. I'm waiting....:)