Lions and foxes and centaurs, oh my! Machiavelli uses these animals to divide rulers into different types. Fox rulers are sly but can't defend themselves, and lion rulers are strong but stupid and fall into traps. Then there are fox-lion hybrids who, besides looking really freaky, combine the best of both worlds.
Machiavelli points to Severus as a very foxy lion:
If we look carefully at what Severus did, we find he played both the ferocious lion and the cunning fox very well; he was feared and respected by all parties and he managed to avoid being hated by the army. (19.16)
We guess his son, Antoninus, didn't take after his dad, because he is all lion. He could have been a great leader, "But his cruelty and ferocity were overwhelming and unspeakable […] in the end he was killed by a centurion while among his soldiers" (19.17). Too busy roaring there, eh Mr. Lion?
For more about lions and foxes, check out what we have to say in "Symbols."
More than any other characterization tool, Machiavelli uses actions. Figures, right? It's plain and cut and dried. This guy is awesome because he did this. That guy is awful because he did that. Since Machiavelli is trying to make a rational guide to being great, it makes sense. It is simple and to the point. There's no way for you to get confused.
Let's look at Machiavelli's favorite example of prowess, Cesare Borgia:
As always Cesare Borgia offers a good example. He invaded Romagna with an army entirely made up of French auxiliaries and took Imola and Forlì with them; but since he felt they weren't reliable he turned to mercenaries as a less dangerous option. He hired the Orsini and Vitelli armies, but when he found that they dithered in battle and were disloyal and dangerous, he had them killed and trained his own men. (14.4)
First, Machiavelli tells us straight out that Cesare Borgia is awesome. Second, he lists the actions that make him awesome, namely killing the mercenaries that he was using and training his own men. (Mercenaries are a pet peeve of Machiavelli's.) This tells us that Cesare Borgia is (a) awesome, (b) super violent, and (c) awesome because he is super violent. Characterization: accomplished.
Notice that this works differently from other works similar to The Prince, where there is no way that Cesare Borgia would ever be the good guy. It's not just that Machiavelli uses actions to characterize people from history, it's that he does it in a totally new and shocking way.
On the other hand, we have Scipio, who Machiavelli makes sure to tell us is not awesome because his actions are moral. In fact, his "moral" actions make him a bad leader:
Scipio was an extremely rare commander not only in his own times but in the whole of recorded history, but he was too easy-going and as a result gave his troops a freedom that was hardly conducive to military discipline … If Scipio had gone on leading his armies like this, with time his temperament would have undermined his fame and diminished his glory, but since he took his orders from the Senate, not only was the failing covered up but it actually enhanced his reputation. (17.8)
Let's look at it again. Scipio is (a) too easygoing, (b) this close to being a failure, and (c) nearly a failure because he is so easygoing.
Get Machiavelli's gist yet? Actions speak louder than words, and in Machiavelli's mind, actions better give results.
It's not super interesting, but it's to be expected of Machiavelli. This form of characterization is cut and dried, just like actions. He tells it like it is: "I've mentioned four exceptional leaders but now I want to bring in a lesser man, Hiero of Syracuse" (6.9). Or let's not forget this one, "Pope Alexander VI never did anything but con people" (18.4). We get the picture.
There are plenty more, but the idea is always the same. Machiavelli just tells us what we need to know about these guys so that he can cut through the unnecessary fluff and get down to business.