some more ideas you can talk about:
- Main characters seems to be ambitious than prudent -> Heroes are defined for their good deeds for the community, not for the deeds they committed in the name of revenge/ ambition. Explore Jason's political ambition and Medea's emotions.
- How did Euripides then explore what it is to be a villain. Is the notion really explored in Medea?
See, but I feel like the first point is working from a pre-existing idea of heroism - not one that is inherent in the text, or that has an exclusive claim to validity. That's why I think determining what you think 'hero' means (in the context of Euripides and the text) is really the interesting part, the fulcrum, of the question. That definition will then give you your definition of villain, in the corollary. Because I don't think heroes are defined, in the context of Euripides and the text and its moment in history, in terms of good deeds for the community. Look at the 'hero' of Jason, for instance...