Their baby sister
Lilly Fuentes, She's a 7 year old little girl. She might be young but her life is horrible. Her older brothers are Mike and Vic Fuentes, drummer and singer for the band, Pierce The Veil.
They're gone a lot and have their own homes, so they don't know what happens to her when she's alone with their parents. Their parents are evil to her, they didn't want a 3rd child and you could tell, they pick on her and abuse her daily.
One day, her dad takes it too far and nearly kills her, but luckily, Vic and Mike are to the rescue, getting her out of that house and never to return again.