Both. If you think either one of them is "the bad guy", you've failed to understand the Hellenic pagan mindset. They didn't share the Christianity-derived vision of every fight as a proxy war between ultimate good (God) and ultimate evil (Satan). They thought of war as a clash between tribes over a conflict of interest. Each of these men was an ideal of masculine virtue, fighting for the cause of his tribe. Which is what heroes did. Modern Christians think that wars shouldn't happen, because everyone should be on the side of God, which is one of the two sides. Hellenic pagans thought that war would happen, because tribes and nations inevitably have conflicting interests. So, in their worldview, it was entire possible for two righteous, virtuous, admirable heroes to make war against each other.