'I will control everything so nothing bad happens again' (Mycroft), 'Caring about people makes you feel Bad when they die, I will not care' (Sherlock), and 'Maybe if I'm quiet and do everything right no one else will die' (Trevelyan).

Yup, that's more or less my headcanon as well. Although my Sherlock is a lot more self-destructive about it. I also randomly gave Mycroft a Freudian spin but that's because my brain does Freudian spins on stuff these days.