File Orestes alongside Oh Dae-Su from Oldboy, The Bride from Kill Bill, Django from Django Unchained and Matilda from Leon: The Professional. This dude has one thing on his mind: revenge. At least, until he's done the deed. Then he only has purification on his mind.
But to really understand the character of Orestes in The Eumenides, you've got to know his back-story. This back-story stretches all the way back through the Oresteia trilogy—yup, "Oresteia" is referring to "Orestes." Let's start at the beginning, way, way back in the mists of the prehistory of Agamemnon, which is Part I of the Oresteia.
Ahem. Deep breath. Here goes:
So Orestes's grandfather, Atreus, butchered the children of his brother, Thyestes, and served them up to him for dinner. Way to be Hannibal Lecter-levels of horrific, dude. Then Orestes's father, Agamemnon sacrificed his own daughter while on his way to make war against the Trojans. Hmm. Being a child-killer runs in the family, we guess.
When Agamemnon came home from Troy he got murdered by his own wife, Clytemnestra (Orestes's mother). Then, Clytemnestra shacked up with her accomplice in the murder, Orestes's uncle Aegisthus. As you can see, Orestes comes from a pretty messed-up background. When Orestes came of age, he goes to the oracle of Delphi where he receives a prophecy from the god Apollo telling him to kill his mother in revenge for his father.
And that's exactly what Orestes did, in Libation Bearers, Part II of the Oresteia trilogy. Now, killing your own mom sounds like just about the worst thing you can do, but Orestes wasn't a purely cold-blooded killer. Sure, he iced Aegisthus without giving it much thought, but, when it came down to the final confrontation with his mother, he wavered.
It was only when his buddy Pylades reminded him of Apollo's oracle, that Orestes firmly decided to stay the course and carry out the god's command. And yet, as soon as he had done the deed, Orestes had a massive crisis of conscience. Not only did he begin to doubt whether his mother had actually killed his father, but he had a horrifying vision that the Furies (divine spirits of vengeance) were pursuing him. At the end of that play, the Furies were visible only to him, so it wasn't clear if he was totally nuts or not. The matter remained unresolved, because Orestes ran off to Delphi to be purified.
The Eumenides begins in Delphi outside the temple of Apollo where Orestes has come to be purified. When the Prophetess of Apollo enters the temple and then runs away in horror at seeing the Furies, seems to show that Orestes wasn't totally nuts, and the Furies really do exist. Also, the Prophetess's description of Orestes mostly agrees with our earlier picture of Orestes as a guy fundamentally devoted to the gods.
This can be seen in the fact that he has come to the temple holding an olive branch wrapped in wool, which was in keeping with religious custom. Also, even though the Prophetess is outraged that he has come to the temple holding a bloody sword—that was a definite no-no—this may actually be the exception that proves the rule, because he's just following Apollo's instructions.
When Apollo tells Orestes that he has one more journey to make—to Athens—our hero shows his obedience once again and sets off on his journey. By the time we meet Orestes again, in Athens, he seems like a new man. Even though his obedience to Apollo is unchanged, Orestes's attitude is now one of strong confidence:
(Orestes): "The bloodshed is now drowsily asleep and wasting away from my hand, with the pollution of my mother's killing washed off; for while still fresh it was driven out at the hearth of the god Phoebus in a purification where young pigs were killed. It would be a long story for me from its beginning, all the people I approached harmlessly with my company; time cleanses everything as it ages." (280-286)
Huh. Where was this "time cleanses everything" attitude when he decided to kill his mom, we wonder? This quote suggests a couple of not-so-flattering things about ol' Orestes. He feels that, (a) he has been purified of his crime, (b) what he did was justified, and (c) Apollo will get him off the hook. It also shows what he was most worried about was the fact that people, sensing his guilt, would stay away from him… not the fact that he just offed his mom.
But say what you will about Orestes' morals; he knows how to influence the powerful gods. He promises Athena a lasting peace between the Athenians and the Argive people if she lets him off the hook for the whole matricide thing:
(Orestes): "Now my lips are pure as I call reverently upon Athena, this land's queen, to come to me with her help; and without warfare she will gain myself, and my land, and the Argive people as her true and ever-faithful allies. […] I wish she may come—a god can hear even when far away—to set me free from what I have here." (287-298)
Imagine how this would play out if it were a scene in a modern courtroom drama rather than a play with the goddess Athena acting as the judge. Orestes is basically saying "If you let me go, I'll give you all my property and pull some serious political strings for you." Whoa, corruption. This speaks both to Orestes' corrupt nature and also the corrupt nature of the gods—if you scratch their back, they'll scratch yours.
So, while Orestes may be our hero, he's anything but heroic. He's way more nuanced and flawed than you'd expect from a play this old, right? He's more like a character on an HBO show than a knight in shining armor. He's a brown-noser, he's unrepentant, and he's adept at wheeling and dealing.
But he's also as good as his word. At the end of the trial, Orestes immediately checks out for Argos, promising to make his city an ally of Athens forever.