Euripides does not endow the Chorus in Medea with much in way of transformative power. The role of the Chorus is to communicate the destructive levels of human action between Jason and Medea. In many respects, the Chorus is similar to the reader. Like the reader, the Chorus is appalled at Jason's treatment of Medea. Euripides develops the Chorus as being persuaded at the mistreatment that Medea endures:
Back to their fountains
the sacred rivers are falling;
The cosmos and all morality
turning to chaos.
The mind of a man is nothing but a fraud,
One day the story will change:
then shall the glory
or women resound,
And reverence will come to the race of woman,
Reversing at last the sad reputation of ladies.
In this capacity, the Chorus's role is designed to offer sympathy to Medea for what she has endured at Jason's hand. In this regard, the Chorus's function is similar to that of the reader who cannot accept such a brazen display at disrespect given all that she had done for her husband.
Once it becomes clear that Medea's revenge crosses a particular path of no return, the Chorus's function is to express outrage at what she is planning to do. The Chorus articulates how limits must be in place, something that Medea has eviscerated with her plan. When it becomes clear that the Chorus cannot embrace what Medea is about to do, Euripides designs the Chorus as the voice of reason where none seems to exist:
How will you keep the tears from your eyes when you look at them, how will you keep your resolve to kill them? You won't be able, when your sons fall down and plead, to soak your hand in their blood with your daring heart.
The Chorus operates in the role of advisor to Medea as they say, "I want to help you and aid the laws of humanity; please don't do this." The Chorus operates as a voice of restraint when it becomes evident that Medea is focused on revenge in the most heinous of ways. When it is clear that Jason has little idea of what is planned, the Chorus offers a sad note of support in lines such as "I groan with your pains." Like the reader, the Chorus is knowingly helpless, incapable of doing anything else other than to voice emotion about that which lies ahead.
When blood has been shed at the end of the drama, the Chorus's role is to speak towards the power of the divine. Euripides constructs the role of the Chorus as one that affirms the power of the divine as the only way to make sense of the complications that human beings develop. The Chorus repeatedly speaks to "god's will" and how the only solution for "heart oppressing wrath" is complete submission towards the ways of the divine:
Zeus dispenses many things from Olympus, and the gods bring to pass much that is unexpected. What was believed is not borne out, while God finds a way for the unforeseen. So it was in what has just passed.
In affirming that the role of the divine is the only constant in a world besieged by human insecurity, pain, and doubt, there is a clear affirmation of the Chorus's role. They end up becoming no different than us and our own experiences in the epic struggle to simply be human.