The king who did nothing
In the beginning of the second scene, the King is told Medea poses a great danger for himself and for his daughter. The king decided to tell Medea to leave the city but does not do anything too drastic. Ironically, his unwillingness to act ends up costing him both his daughter's life and his own in the end.
Saved by the one whom she wanted to kill
Medea is bent on getting revenge against her former husband and is willing to kill him without feeling a shred of remorse. Ironically, Jason had the power to save his future wife, all he had to do was allow the King to kill Medea. Ironically thus, Medea is saved by the same man she planned to kill.
Destitute wife
Medea helped Jason in his quest to gain fame and riches. Jason could have not succeeds were it not for Medea and as such everything he had was because of Medea. Ironically, when Jason left her, Medea was left with nothing. She suddenly found herself in the position of not being able to provide for herself and her children even though the riches her husband acquired were all because of her.
He is a good man
Medea despises Jason for what he had done to her and wishes to see him suffer. She plans to get revenge on him on all costs and even sacrifices her own children in the process. Considering all these, it is ironic to see how Medea still portrays Jason at times in an extremely positive way. Her descriptions may be used here to transmit the idea that even though Medea felt resentment towards Jason, she still had some feelings of affection for him.
The innocent suffer
Another ironic idea is the fact that those who suffer at the end of the play are those who are not to blame for the actions which took place. The characters who died were Medea's children and Jason's future wife, three innocent people who had nothing to do with the conflict between Medea and Jason. This proves that justice is not always what one expects and that in the pursuit of revenge, innocent people are often the ones who are most affected.