Blame themselves and believe it is their own fault. Are desperate to 'fit in'. View is very often reinforced by the attitude of adults in their lives. It is highly unlikely that they will seek help. They neither bully nor are victims.
Every pupil has the right to a safe school and the responsibility to stop bullying.
Support the victim. Identify what has happened. The aim of any intervention must be to stop the immediate abuse. Help the bully change his or her behaviour. Make the peer group aware and ask them to help the victim.