Rita will be a changeling who's trying to make it on her own, but she spent so much time in the fae realm that she doesn't really know how to function all that well in the human world. So she'd have spent a short time at the Sanctuary a couple years back, when she first left the fae realm. She grudgingly comes back every once in a while, for a hot meal and a roof over her head, though she never stays long and keeps insisting that she's totally fine by herself.

So Helen could maybe know this antisocial teenager from those occasional stays over the past couple years!