A ward is a member of a noble House who has been taken in by another noble family to be raised for a time. The practice varies, with it sometimes being undertaken voluntarily, for example, to help prospective heirs learn the customs of other regions of Westeros as part of their education. It can also happen involuntarily, with the "ward" actually being a hostage to force his or her family into good behavior or until a ransom is paid. Sometimes, as part of marriage alliances, one of the betrothed is taken as a ward so he or she can get to know his or her future spouse.
In cases of wards who are political hostages, because they are of noble blood and valuable in the peace agreement, they are not treated as mere prisoners to be thrown in a castle's dungeons. Such wards are treated with full courtly etiquette as noble guests, and quite often are treated as essentially foster children of their "captor". Such hostage-wards are given free run of the castle they are staying in, eat at the lord's table, and are essentially raised alongside the lord's own children. The only limit is that they are forbidden to leave the bounds of their host's lands and return to their original homes.
While wards fall under the Lord's protection as a member of his household, their relationship is not technically seen as enjoying benefits of guest right, particularly for wards who are political hostages. Thus Theon Greyjoy was not accused of violating guest right when he betrayed the Starks, which would have been a far worse crime.
Theon Greyjoy was given up by his father and surrendered to the custody of Lord Eddard Stark following Balon's failed rebellion, which ended with the deaths of his two elder sons, Rodrik and Maron. Although Theon was raised and educated by the Starks and treated well, he was nevertheless a hostage as well as a ward, something that rankles with him when Tyrion Lannister taunts him over the matter.
As part of a marriage alliance arranged by Tyrion Lannister, Princess Myrcella Baratheon is taken to Sunspear as a ward of House Martell so she will get to know her betrothed, Prince Trystane Martell.
As a ward is theoretically a member of his host family, he can give away a bride from his host family if her father or brothers cannot. As such, Theon Greyjoy gives away Sansa Stark to be married to Ramsay Bolton.
- Theon Greyjoy: "Sansa of the House Stark comes here to be wed. A woman grown, trueborn and noble. She comes to beg the blessings of the Gods. Who comes to claim her?"
- Ramsay Bolton: "Ramsay of House Bolton, heir to the Dreadfort and Winterfell. Who gives her?"
- Theon Greyjoy: "Theon of House Greyjoy, who was...who was her father's ward."
- — Theon Greyjoy[src]
In the books
In the A Song of Ice and Fire novels, wardship or fostering is seen as an honorable and common tradition. The ward is an honorary member of the House for the duration of his or her stay, including having a raised social status if he or she is from a lesser House. Fostering frequently results in close ties and sometimes alliances being formed between Houses from different sides of the continent. Most notably, Eddard Stark first met Robert Baratheon when they were both wards of Lord Jon Arryn of the Eyrie, leading to their lifelong friendship and an alliance between their Houses.
- Prince Quentyn Martell was a ward of Lord Yronwood at Yronwood.
- "Big" Walder Frey and "Little" Walder Frey, both grandsons of Lord Walder Frey, were wards of Catelyn Tully at Winterfell as part of the alliance between House Stark and House Frey.
- Planned wards:
- Jon Arryn planned to send his son Robert Arryn (renamed Robin Arryn in the TV series) to Dragonstone to be the ward of Stannis Baratheon, but he died before this could come into practice; after Jon's death, King Robert Baratheon planned to send Robert Arryn to Casterly Rock as the ward of Tywin Lannister, and this plan is also foiled because Jon's wife Lysa Arryn returns to Eyrie with his son hurriedly. It was revealed that Lysa poisoned Jon because she did not want Robin to be sent away from her as a ward.
- Ramsay Snow planned to send Talia Forrester to the Dreadfort as his House's ward but her twin Ethan rejects this decision.
In real life
In real life, it has been common practice throughout history for defeated lords to hand over one of their children as a hostage to be raised as the ward of a victorious lord. The hostages were treated well according to their social rank, but kept as a guarantee that should the defeated party break the truce, their children could be easily killed. The practice dates back to ancient history and there are numerous examples from the time of the Roman Empire, e.g. Aetius, the last great Roman general who lived during the fifth century and defeated Attila the Hun, knew Hun battle tactics because he had been raised as a political hostage at the Hun court. The practice of handing over hostages to be raised as wards was also commonly used in the Middle Ages, and even into the Early Modern era.