I can't remember where I found this story and I'm hoping someone who has read it knows where it is, or something similar.

It started with a brother babysitting his younger sister, and is tired of her. It escalates when he tricks her into wearing his father's big "onaholed" teddy bear, his father comes home and the brother panics leaving his sister in his father's bedroom stuck in the bear. The father is drunk and doesn't realize stuff is moved in his room. He quickly just does his nightly ritual involving his big cock and the bear in bed. It feels way better than it should but he just fucks her for hours with his cock in her, even while passed out. The brother tries to retrieve her and (here is where my memory gets fuzzy) he ends up in the hallway with her still inside and something happens. Next thing I remember is the family dog mounts the teddy. (Fuzzy Memory) Then the daughter becomes sexually broken, slightly addicted to her father's cock, he figures it out and the family environment improves as a result.