I think Bonnie's background as a recovering drug addict isn't just there to flesh out her character, but will be a major plot point in one of the chapters.
My prediction is that she is going to fall of the wagon, and steal painkillers from the group to get high. You're then going to be forced into making a major decision regarding her fate over the theft.
Another possibility is that since she is the only one who goes with Tavia no matter what, that she'll end up stealing from the settlement, and that it will cause a rift that ends up either getting your character kicked out, or choosing to leave the settlement.
So what are your predictions?