If Lorenzo is the primary antagonist, Pedringano is the secondary antagonist. And in lots of ways, he's even more important to the action of the play than Lorenzo. That's because he keeps the action moving. He's like the worker bee of bad deeds.
Need some private intelligence on others? Call Pedringano. Need someone killed? Called Pedringano. Need to have someone take the fall for you? Call Pedringano. But in respect to the latter task, you'll have to get crafty to pull this off, because Pedringano is the kind of self-server who only acts for himself.
Here's a question we've been mulling for a while: why does the play need a secondary bad guy?
Well, for one thing, the other really bad guy (Balthazar) can't hack it. But the other reason is that Lorenzo is an aristocrat. Think about it: we can't have the noble Lorenzo going around getting his own hands dirty. That's a job for the servant class. At least that's the way Lorenzo sees it. And like any good servant (or bad one, in this case), Pedringano does all the dirty work. And say what you will about his horrible deeds, but the dude does his work ambitiously and with a light heart.
Even though he's just as much a killer as Lorenzo, at least he has motives: money and ambition. Well, that and he's really into saving his own skin. As Bel-Imperia's servant, Pedringano is supposed to be responsible for keeping her secrets, but after Lorenzo tempts him with gold (and threatens him with a sword, we might add), the servant quickly says, "Oh, stay, my lord! She loves Horatio" (2.1.78). We told you he's quick to save his own skin. But after this he makes sure to get paid, son.
So yeah, he's really ambitious. He calls this ambition his "attempting spirit," and his spirit is all about the Benjamins (3.3.3): "Here is the gold, this is the gold proposed; it is no dream I adventure for, But Pedringano is possessed thereof." The language is a little difficult here, but he's saying that the gold in his hand is real, and so is the gold "proposed" (or, the gold still to come). He doesn't struggle for some abstract dream, but rather for what he can hold in his greedy lil' mitts.
He's ambitious. He's a materialistic. And not a speck of morality will get in his way.