25 years ago I undertook a study into different aspects of bullying (perceived, reported, kept secret etc) in the secondary school where I was on the pastoral team,
I learned some things which surprised me, others would nowadays be obvious but we were aiming to not only address the bullying itself, but also how some children seem "immune" and for those whose lives are a misery, to provide a safe haven (obvious today, but apparently not then) as well as strategies for the times of day when teacher supervision is not already practical.
One boy sticks in my memory, he was a classic "candidate" for bullying if you know what I mean. Very very bright and not afraid of being seen as a high achiever, polite, well spoken, fairly conservative in his appearance and a bit of a loner. Yet he never suffered. Why?
His mum had chosen to invite a group of children to his last birthday party while he was at primary school, a group which included a local "bad boy" the scourge of the teaching staff, already known to the authorities at 11 and a regular tearaway. He didn't get invites to many parties,( if any) and from that time on, the other boy in question was "my mate, and don't anybody mess wiv 'im"
Not necessarily the best foundation to underpin an absence of bullying, but in this case it worked.