Usually bullies check out / groom their own management and HR first.
So they’ll want to find out as much as possible about their own management – is there something their manager doesn’t like doing, part of their job the manager isn’t good at? Then the bully will try to take over those tasks for their manager – become indispensable and they’ll want to check out HR too, are they intimidatable? The bully needs to check out what is likely to happen if someone complains about their behaviour. I bet HR were terrified of Weinstein!
