I was reading the discussion in a fantasy club and you said you were looking for plot ideas for fantasy and fan fiction....how about this:
(Frozen fan fiction) There are other people that have ice powers, same as her. Anyways, two boys with ice powers show up at the castle willing to train her powers so she can control them better with one small cost: Elsa must be willing to help fight (Insert group) for peace of another land. (The end because that was as far as I had gotten)
Hope you like the idea!