Shasta, Aravis, Bree and Whin all want to leave Calormene and escape to Narnia. (Bree and Whin are talking Narnian horses who have been captured and have worked in Calormene, without revealing their abilities.) Shasta was found in a boat by a fisherman, who has been hard on him. Aravis is escaping an arranged marriage with an old, ugly man. (Shasta and Aravis are perhaps 15 or so. Both are human.) The four set out for Narnia. They are separated, but eventually get back together, and finally make it to Narnia.
Aravis, Shasta and Bree (who has been a warhorse of a Calormene nobleman) are tempted to pride, and succumb to it. Each of them wants to look good. Bree is afraid that he will look bad in comparison to free Narnian horses. Shasta tries to strike up grand airs. Aravis looks down on Shasta.
Aravis and Shasta quarrel frequently.
Aravis has no concern for a slave girl, whom she drugs, so that she can escape. Aslan punishes her by scratching her in an amount equal to the suffering caused by a lashing of the slave girl.
Shasta steals some supplies, so that the four of them can travel through Tashbaan
Susan, Edmund and Tumnus plan to deceive the Calormenes, in order to escape Tashbaan.
Over and over, Bree is tempted to pride, one of the seven deadly sins.
Rabadash, the Calormene prince, may have lusted (one of the seven deadly sins) after Queen Susan of Narnia. He set out to war on Archenland, without a provocation, and planned to do the same to Narnia, itself. This was probably avarice, one of the seven deadly sins. He was also wrathful, another deadly sin, when he was defeated by the troops of Archenland and Narnia. Aslan struck at his pride, by turning him into a donkey. He was never tempted to leave Tashbaan again, after he was miraculously restored to his human form in front of a large crowd of people, believing Aslan, who told him that he would become a donkey permanently if he left it. Aslan warns him:
"Rabadash," said Aslan. "Take heed. Your doom is very near, but you may still avoid it. Forget your pride (what have you to be proud of?) and your anger (who has done you wrong?) and accept the mercy of these good kings." C. S. Lewis, The Horse and His Boy, New York: Collier, 1954. p. 208.