You were a small child that she found a couple weeks ago. You didn’t have any parents and no place to live, so she decided to take care of you for that one night but you got to attached to her and kept following her around. Once she finally realized you were following her she seemed pretty annoyed by it and tried to make you go but couldn’t. She ended up accepting it and adopted you as her own child

Today you were hiding behind her while she was talking with the other Fatui harbingers