The cavalier is one of the least flexible classes in the base rules. The class grants a single choice at first level (what order to join), and a very few bonus feat options (six over 20 levels, half of which must be teamwork feats and half combat feats), and no other opportunities for customization. The only other classes with so few customizable abilities are spellcasters, who can create very different types of characters with spell selection and complimentary feats. Certainly players can use weapon proficiency choices and the feats gained by all characters to fine tune a cavalier's development, but in many ways doing so may actually weaken the character. A cavalier's focus on mounted combat, and regular acquisition of abilities tied to charging, makes it difficult to justify not selecting the lance (which does double damage on a mounted charge) and the chain of feats that end in Spirited Charge (allowing the cavalier to deal triple damage with a lance charge).
And yet, for most players, cavaliers have come to represent the iconic knights of Western Europe, with a special mount, special abilities tied to challenging and charging foes, and an order that grants them real power. And with a few tweaks, they can also be used to represent the heavy cavalry of other civilizations, from Japanese samurai to Arabic furusiyya, Egyptian mamluks, Greek hippeus, or even Mongul horse archers. But, the further a character concept is from the core chivalric knight, however, the harder it is to make the cavalier feel right, even when many of the key functions of these different warriors castes are very similar.
So before building a 'talented' version of the class, we must ask - just what defines the core concept of a cavalier, if it's not their role as heavy cavalry or adherence to an order? If we create other class options, what makes a cavalier who decides not to focus on horseback charges and a knightly order different from fighters? Just what is the essence of the class as a whole, once a wider range of character concepts can be created by a more flexible design?
To answer that question, it's important to look at the alternate class and archetypes that are tied to the cavalier in the core rules. It's easy to see how samurai can be represented as Asian cavaliers (though the role is not a perfect match to historic samurai), but the various archetypes show an interesting trend as well. From emissaries to huntmasters to standard bearers, many of the cavalier archetypes are members of the ruling caste (or the sworn servants of that caste) who serve in a martial capacity without being tied to the role of heavy cavalry.
The Genius Guide to the Talented Cavalier is our answer to that question: a class designed around the idea of a warrior caste tied to the ruling class of society. Some cavaliers are clearly traditional knights and samurai, while others are clearly less so, but all cavaliers are trained to both fight and serve a role within their home culture. By using this broader idea of what a talented cavalier is, allowing both players and GMs to use the Talented Cavalier class to fill the ranks of noble knights, feared slave-warriors, honor-bound hunters, determined sheriffs, or even musketeers in dutiful service to their queen.