The season three trailer left us with a lot of questions, specifically about who the British teenager narrating it might be. She's introduced right away in season three as Ani, the daughter of an in-home nurse who's living with the Walker family to care for their ailing (and racist) grandfather.
Over the season Ani gets close to Bryce, a relationship that's pretty odd from the start (What was the show trying to do, here? Humanise a cold-blooded rapist by showing him play cards?). Despite their warm interactions — which range from the aforementioned card games to having sex — the season opens with a scene of Ani furiously scrubbing what looks like blood off of a white shirt. In the end, though, it's merely a red herring since she's not the one who kills him. (The stain on her top was simply red paint from Jessica's Hands Off protest during the school's Homecoming game.)