We at Shmoop do our best to be as non-judgmental as possible, but it really is kind of hard to find anything redeemable about Atreus. At a young age, he kills his stepbrother, Chrysippus, with the help of his brother, Thyestes. Most people would probably agree that murdering your stepbrother is a pretty awful thing to do, but Atreus actually manages to top himself in terms of awful deeds. When Atreus kills Thyestes' sons, cooks them, and serves them to their unknowing father for dinner, Atreus may just win the award for most thoroughly messed up dude ever. It's sort of hard to imagine a worse thing anybody could possibly do.
Okay, sure, Atreus was provoked into his awful deed. Thyestes did sleep with Atreus's wife, steal his golden fleece, and try to steal the throne of Mycenae. However, we're guessing we're not the only ones who see Atreus' reaction as more than a wee bit excessive. Like, what did the kids ever do to deserve being chopped up and eaten? Later on, Atreus tries to get the final revenge by having Thyestes' son, Aegisthus, murder him. This plan backfires, however, when Aegisthus figures out that Thyestes is his father. In the end, Atreus gets what's coming to him when Aegisthus makes shish-kebabs of his uncle's guts.
Atreus might win the award for most messed-up revenge ever when he tricks Thyestes into eating his own children, but it's not like Thyestes is a particularly mellow dude either. Along with Atreus, he murders his half-brother, Chrysippus, at a young age, and then proceeds to do all kinds of other jaw-droppingly awful things. Thyestes starts the feud with his brother by sleeping with Atreus's wife, stealing his golden fleece, and trying to take the throne of Mycenae. It's pretty hard to justify Atreus's particular brand of bloody justice, but there's no getting around the fact that Thyestes brings his misery on himself.
Later in the story, Thyestes manages to find even more awful things to do. An oracle tells him that if he has a son by his own daughter, Pelopia, that son will kill Atreus. So, Thyestes then proceeds to force himself on his daughter and impregnate her. In some different versions of the story, Thyestes doesn't receive a prophecy and rapes Pelopia not knowing that she's his daughter at all. Though this scenario does make Thyestes an unintentional incestuous rapist, he's still a rapist. No excuse for that. In the end, both Thyestes and Atreus show themselves to be ultra-brutal human beings, and one can't help but think that the myth-makers who came up with this legend are holding both brothers up as examples of what not to do. (Or at least, we hope so.)