Possibly the sibling of Sabrina Fuller. We think. We are taking a bit of a leap here because although she/he is asleep in the Fuller house and therefore not the little girl, uh, little boy who opens the door to Veronica, who else could she be? Lynn Echolls? Does Lynn Fuller's apparent non-existence when Veronica babysits for the family help or hinder a sensible conclusion? Work it out for yourself in 1.17 "Kanes and Abel's" and 2.07 "Nobody Puts Baby in a Corner."
All bios: 2.07 1.17