Oh man...this is about to get depressing 
When my MC, Auriella, was 10, she had to watch her mother, Beira, wither away due to an illness. She died in her arms and Auriella was adopted by her best friend's, Oriana, family.
In this one, my MC, Mirella, was forced to watch as her fellow fairies were struck down by humans with swords in her hometown of Verhmina, a place humans shouldn't be able to enter. Her parents died right in front of her and her brother practically sacrificed himself to protect her.
And finally, my MC, Valerie/Cleo, was literally bullied to her death (pushed off the roof of a tall building, though was it truly an accident? 
) and it will haunt her for a long time.