Katie is the daughter of Regina and Robin but Regina doesn't know it. See, when her and Robin did it, the infidelity potion was broken because, well, true love. Anyway, out of jealousy Zelena let the pregnancy progress until the ninth month and a few days before Katie was due, Zelena  ripped her niece from Regina's womb, and erased all memories of the pregnancy from Regina's mind before sending her to Arendelle where she was adopted by Anna and Kristoff. Her adoptive aunt is Elsa. She has magic but rarely uses it and is a very good archer. Elsa wants her to learn snow and ice magic but until she gets it right she gets the occasional snow cloud over her head. If you say the word 'snow' her allergies act up, because of the cloud. The snow becomes closer and falls faster around Katie. The only way to stop it is with snow and ice magic. She has Regina's dark hair color and her eyes are blue