Poseidon's infant son, Percy, and Athena's next born daughter are promised one another's hand in marriage due to a promise made by Zeus. 22 years later, Annabeth and Percy find out. Will their brother/sister relationship be ruined, accept, and continue their lives as it was before the marriage? Or, do they learn to love, getting to know one another? AU, not AH. Really OoC.

Mai's half-sister is a princess of the water nation and the only love of Zuko's childhood. Yet when the fire nation attacks her home everything that she loved there is destroyed; leading to a journey of forgiving their pasts, and learning their future.