A ward is a minor that can't be with their birth parents (usually due to their death), so the minor is assigned by the court to another adult called their guardian.
A court may take responsibility for the legal protection of an individual, usually either a child or incapacitated person, in which case the ward is known as a ward of the court or a ward of the state.
In Rain[]
Rain became Fara's ward after her mother (Liriel Flaherty) died and her father (Marcus Flaherty) walked out on the family. Those events happened before the start of the story.