Themes: A Storm of Swords
Duty is the cornerstone of the Seven Kingdoms' feudal society; the smallfolk work and pay their taxes while the highborn play roles assigned to them by family, fate or choice. Everyone has a duty, whether it be to another person, a group of people, or the realm; duty is what differentiates the people of the Seven Kingdoms from the wildlings beyond the Wall. Duty breeds discipline, and discipline begets order - without duty, disciple or order, the men and women south of the Wall would be no different than those who live beyond it.
In Westeros, performing one's duties despite one's personal feelings is considered to be exemplary behavior, honorable even. Some even turn duty into armor in order to protect themselves from pain or hurt. In A Storm of Swords, an example of this would be Sansa Stark, who is forced by the Lannisters to marry Tyrion Lannister. Sansa has grown up with songs and stories about true love, handsome knights and beautiful princesses - Tyrion is not the type of man she thought she'd marry. Although Tyrion treats her kindly, Sansa finds that she cannot love him, but she does her duty as his wife, going where he tells her to go, asking his leave whenever she wants to go to the godswood to pray, even sleeping on the same bed. Although she finds the entire situation unfair, she does her duty as Tyrion's wife, all with a touch of grace and courtesy; as she tells Tyrion "Courtesy is a lady's armor."
Then there are those who chose duty over birthright. Despite his father wanting him to return home and take his right place as the heir of Casterly Rock, Jaime insists that he is only interested in being the Lord Commander of the Kingsguard and nothing more. Jaime's decision to perform the duties of the office that he has been promoted to rather than accept his birthright drives a wedge in his relationship with his father.
Even kings sometimes forget their duty. In the second half of the book, Stannis Baratheon is reminded by his Hand, Ser Davos Seaworth, that a king's duty is to protect his people, otherwise he is no king at all. Davos says that just before reading out a letter from the Night's Watch, one that calls for all the kings of the Seven Kingdoms to send more men to the Wall to stop a wildling invasion, a request which has fallen on deaf ears and received no reply. In the end, Stannis remembers that his first duty is to his people - he brings his army to the Wall, the only King to answer the pleas of the Night's Watch.
Vows & Oaths
If duty is the brick wall holding up the Seven Kingdom's feudal society, then vows, and oaths must surely be the mortar which holds everything in place. A vow or oath is never given lightly because keeping it is a testament to how honorable a person is; oathbreakers are reviled and vilified for going back on their words. Trust, once lost, is hard to regain.
The vows of the Kingsguard involve swearing to protect the king and the king's family, even at the cost of their own lives, and to obey the King and keep his secrets. Jaime Lannister is the perfect example of man who broke his vows and is consequently vilified for it. A sworn knight of the Kingsguard, Jaime chose his family over his vows, slaying King Aerys II on the steps of the Iron Throne, the king he had sworn to protect. The act earned him the derogatory epithet Kingslayer. That single act has followed him everywhere ever since and nearly always colors his interaction with others, something which secretly bothers him. This can be seen in A Storm of Swords in his interactions with Brienne of Tarth, where he begins to get irritated when she constantly doubts his honor and motives, based on his reputation as the Kingslayer.
The men of the Night's Watch have their own vows - they must protect the Seven Kingdoms against any enemies who seek to pass through the Wall, they cannot own any land, marry or father children. In A Clash of Kings and A Storm of Swords, Jon Snow is wracked with guilt when he joins the wildlings, despite it being Qhorin Halfhand's last orders. He also sleeps with Ygritte repeatedly, knowing that he is breaking his vows of chastity each and every time. When Jon finally escapes the wildlings and return to Castle Black to relay all that he has learned of Mance Rayder's army, some of his black brothers consider him a turncloak for joining the wildlings and sleeping with a wildling woman, but his friends and many of the men acknowledge and accept that Jon did so only for the good of the Night's Watch.
Slavery is outlawed in Westeros but is widespread in Essos, the continent to the west of Westeros. The first two books touch upon slavery, but it is in A Storm of Swords that we first get a more comprehensive look at it. The book introduces the reader to slavery in the form of the famed slaver cities of Slavery's Bay, which is where all of Daenerys' chapters take place in, and where the slave trade is the most rife.
Daenerys seeks to free the slaves in the three slaver cities of Astapor, Yunkai and Meeren. She starts off by buying all the Unsullied that Astapor has to offer; the Unsullied are eunuch slave soldiers renowned for fighting with spear and shield. In a clever feint, she then orders the Unsullied to kill the slavers of Astapor and after they complete the task, she frees them from slavery, and does the same for all the other slaves in the city. Daenerys goes on emancipates the slaves of Yunkai and Meeren. However, after she conquers Meeren, a trade captain lands in Meeren and offers to buy slaves from Daenerys in order to sell them later in the Free Cities; Daenerys is surprised when she learns that some of the Meereenese actually want to be sold as slaves to the trade captain. She goes on to learn that the Meereneese who have volunteered are well spoken and gently born, and will live a comfortable and relatively luxurious life working as slaves in the Free Cities.
Therefore, although it is not mentioned explicitly in the book, the fact that some of the slaves in the Free Cities seem to live a more comfortable life than the smallfolk of Westeros raises the question whether there is much of a difference between the relationship of slave and master and that of smallfolk and ruler, especially if a master feeds and cares for a slave better than any ruler could for his smallfolk. What is the price of freedom, and is being free worth it when faced with the threat of starvation and homelessness.
Although the smallfolk might lack the power, privileges and social mobility associated with the highborn, they do have more freedom in one aspect of their lives: the right to marry whoever they love. This is one privilege that the highborn rarely enjoy. Children from the noble Houses of Westeros can be betrothed to their future husband or wife when they are as young as eight or nine; such marriages are usually planned out well in advance, and for purposes such as sealing an alliance between two Houses, wresting control of the other House's seat through the male heir, winning soldiers from the other House, and a whole lot of other reasons that almost always center around power and stability.
In A Storm of Swords, one of the most prominent example of a loveless marriage forced upon both husband and wife is that of Sansa Stark and Tyrion Lannister. With Sansa's siblings all believed to be dead, Tywin Lannister forces the marriage upon Tyrion so that Tyrion can one day inherit Winterfell through his and Sansa's son. And in one fell swoop, House Lannister would have control of the North.
Then there is the marriage between Lysa Arryn and Petyr Baelish. When Petyr had been simply the master of coin on the king's small council, it would not have been fitting for Lady Lysa, daughter of the Lord of Riverrun, to marry one so far beneath her. But after Tywin makes him the Lord of Harrenhal, Petyr agrees that a match with the Lady of the Eyrie is now not unthinkable. He goes on to marry Lysa Arryn, though not out of love - he does so in order to win over the Vale to Tywin Lannister's cause.
The marriage between Robb Stark and Jeyne Westerling is the best example of the dangers that marrying for love poses to the highborn. Robb Stark had previously promised to marry one of Lord Walder Frey's daughters or granddaughters in order to seal the alliance between House Stark and House Frey. However, Robb Stark breaks the contract when he falls in love and subsequently marries Jeyne Westerling. Lord Walder Frey is exceedingly insulted by Robb's action and recalls all the Freys who had joined Robb's host back to the Twins. With House Westerling having more honor than power, Robb Stark's decision costs him the military might of House Frey, losing a thousand mounted knights and nearly three thousand foot soldiers. At the end of the chapter where he reveals his marriage to Jeyne to his mother, Robb himself admits that he has to win back the Freys, otherwise he has no hope of taking back the North from the ironmen. However, the insult done upon House Frey might be too great for Lord Walder Frey to accept an apology...even from a King.
One of the five men who has declared himself a king is Stannis Baratheon. A Storm of Swords sees him being presented with a moral problem that revolves around the boy known as Edric Storm. Edric is the bastard son of the late King Robert Baratheon, Stannis' elder brother. When Stannis took control of Storm's End, he had Edric shipped back to Dragonstone. The dilemma rises when Melisandre pleads with Stannis to sacrifice the boy to R'hllor; she believes that doing so will wake the stone dragons of Dragonstone as mentioned in an ancient prophecy, stone dragons that will help Stannis win the war. However, Stannis' Hand, Ser Davos, is against sacrificing Edric, with the reason that a king's duty is to protect his people and that Edric Storm is one of Stannis' people.
The fact that Stannis has always prided himself on being a just and fair ruler makes the choice even harder for him. On one hand, he reasons that sacrificing the child to R'hllor will save countless other lives in the war that is to come, if Melisandre's prophecy is indeed true. But, on the other hand, Edric Storm is a boy who is innocent of any crime and by Stannis' own moral compass that would mean it would be wrong of him to sacrifice the boy. Perhaps what Stannis later says to Davos indicates the true nature of sacrifice: that sacrifice is never easy; otherwise it is no true sacrifice.