Being neurodivergent certainly draws bullies' attention. So does lack of self confidence, people pleasing and caring what others think.
If you can teach her to judge them for their bitchiness, cliquiness and cruelty, rather than judging herself, she won't react like a victim so much. Teach her to truly believe that the opinion of vermin who treat others the way they treat her means nothing to her, even if they are popular. If they think she doesn't fit in - good - who wants to fit in with bitchy, cruel cows? She'll say everyone, they are so popular, and you have to explain that just shows what weak sheeple most people are, preferring to side with bitches because they are scared of being targetted themselves.
Encourage her to walk tall, to genuinely think: 'I don't like how you behave, I judge you to be a bad person, so your opinion of me is valueless' about anyone who tries to bring her down. If she is ever threatened physically, escalate it immediately - not just school but police.
And encourage her to develop a friendship group of fellow neurodivergent apparent social outcasts, whether via school or a local ND teens group or a special interest group. These are, ime, the strongest friendship bonds ever. Kind, loyal people who respect each others quirks and interests. There must be a number of ND people in her school year. Ask the HoY or form teacher for advice on who the other picked on children are and ask if they can encourage them to get together socially at lunch times.
If the school has a buddy system, ask them to appoint an older girl or two or three to keep an eye out for her at break and lunchtimes, or when walking home, to ensure she is not picked on.
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