A minor can sue another minor in your state as well as all other states in this country. However, for such a proceeding to commence, the minor filing suit would need to have a "guardian ad litem" placed as the real party in interest for him or her at the time the lawsuit is filed because minors per statute are required to have an adult represent their interests in a legal proceeding.If you file suit through the guardian ad litem, she would have to file an answer through a guardian ad litem or risk being defaulted.From what you have written, you are owed some money for the airfare from your friend. Had the representations she made to you not been made, you would have never bought her the round trip tickets.Good luck.