At first I was confused by 11:05- but it finally clicked.
Opal (Claire) becomes the Grandpa’s eyes, the Dad’s face, and Mom’s pill.
Claire is forced to act as the adult in this household.
She does things for her Grandpa like fetch his cigarettes for him. Acting as his eyes.
She is forced to endure her Father’s long rants in which he talks himself up and insults her to boost his self esteem, acting as his face.
And she is forced to listen to her mother’s rants, calming her down, acting as her medicine.
It’s not just something like physical abuse or neglect, those may be components, but I think the real horror depicted here is one of a child forced to be the emotional foundation for her entire family. All the while, what she really wants, is just to be seen and appreciated.