Brian is a widower with two normal children. He has them in a good private school, tutors them in their subjects, encourages them to socialise with friends, and isn’t abusive.
He is also incurably psychopathic with a fixation on death. If left alone, he would become a brutal serial killer (though he’d never kill his children).
You can prevent this by letting him be an executioner (flipping on the electric chair, giving the lethal injection, firing the shot, etc.)
He would find extreme, even sexual, pleasure in the kills. He would draw up pictures and fantasize about the next one, and there would be a steady enough supply of death sentences for him to do it at least once a week.
- Appoint him executioner and let him live a normal life with his children
- Have him institutionalised before he’d committed a crime, and put his children into an orphanage that gives them bad enough schooling to ruin their future prospects, and where their father’s reputation prevents them from being adopted
- Leave him alone and hope he’ll be arrested for the crimes he’ll commit