I don't think she sees it that way, or knows about it. The way she sees him/ the way the brother acts around her may differ from his actual thought and intentions.
That's why it's so interesting, why does she says he's a murder? What happened that made their relationship strain so much?
That little sister is you ungrateful like why tf u do that to ur older brother whos willing to drop out bcs of you I hate that younger sister