This idea is a bit of a mix, with elements from Tangled, and the series Tin Man, if anyones seen it.
I could be a princess, taken at age four or five from an alternate world, one with elements of magic and industrial revolution, borderline steampunk perhaps. Perhaps the kingdom fought a war with another race of people, and my people one, with me being born days after the victory.
After my fifth birthday, i could be kidnapped by one of that race, and taken with him to this world, earth, to hide me, and punish my parents, the king and queen for their war.
The one who took me could die somehow, and I would be sent to an orphanage, where Im raised, and as my people are natural warriors, i end up joining either the armed forces, or the FBI.
My parents, worried, send out soldiers to all likely parallel worlds to find me, but none have any luck until one finds me on Earth.
you could play the soldier sent to find me on Earth, and brings me back, only to find that the war is back on, and its up to me to harness the magical abilities that were hidden from me by the one who kidnapped me. Thats one idea for it.
if this appeals to anyone, please let me know.