The plays are connected by a common theme of murder as revenge for betrayal, with three of them involving a particularly horrid kind of murder; let's just say that they kept it in the family... Unlike many Greek plays where the gods are seen as omniscient and controlling, Euripides has a slightly more sceptical (almost proto-atheist?) view of the residents of Mount Olympus. Basically, you can't trust the gods to do anything, so you might as well rely on yourself. Unfortunately, that can be difficult if they decide to smite you (but I digress).
In 'Medea', the title character, deserted by her husband Jason (he of the Argonauts' fame), decides that revenge is not a dish best served cold, but an excuse to murder her faithless husband's new wife, his new wife's father and her own two sons. Euripides does a good job of making Medea as sympathetic as possible, painting the ambitious Jason as a success-chasing sycophant who is ashamed of his non-Greek wife, but, by today's standards, Medea does take the revenge thing a bit too far, what with all the murders and then taunting Jason from the air while hovering in a dragon-drawn chariot (which, by the way, is exactly what I want for my birthday).
By contrast, 'Hecabe', widow of the defeated and killed Priam, King of Troy, has slightly more cause for revenge when she learns that not only is her daughter Polyxena to be sacrificed to honour the death of Achilles (whose mentions in the play always conjure up the image of Brad Pitt - stupid film), but that her last remaining son, Polydorus, who was sent away from Troy for his safety, has been murdered by his guardian, Polymestor. It's unfortunate that in addition to blinding her son's murderer, she also gets her handmaidens to do away with his young sons, but that's Ancient Greece for you. If you don't get them when they're young, you may live to regret it when two young strangers hack your head off twenty years later.
Which brings us to 'Electra', daughter of the betrayed Greek hero king Agamemnon, and her brother Orestes. While Orestes is not really convinced about his duty to shed lots of blood, little sis is very keen, promising to top their treacherous mother, Clytmnestra, if Orestes gets rid of her new husband, the usurping Aegisthus. Unfortunately, Electra losses her nerve at the last minute, leaving big brother to do away with his mother, putting himself in big trouble with the gods (there are very detailed divine rules about who you can and can't kill; it can all get a bit confusing at times...).
'Heracles', on the other hand, is a real tragedy. Having returned from the underworld just in time to save his family from the usurping king Lycus (yes, it's not often you use 'usurping' in consecutive paragraphs), the famous hero falls foul of the petty jealousy of his father's wife. Unfortunately for him, his father is Zeus, which makes the woman he has annoyed Hera, Queen of the Gods. As you can imagine, she is not the sort to settle for strategically-placed banana skins or two flat tyres on his chariot, instead sending poor Heracles mad and making him kill his wife and three kids.
Joking aside, 'Heracles' is extremely touching. Euripides sets a scene where the reader is prepared for Lycus to kill Heracles' wife, father and children, and when Heracles appears in the nick of time, the reader experiences the same sense of relief that the characters do. Of course, for those watching the play in the era it was written, this was a part of the shared cultural knowledge, and everyone would know exactly what was going to happen next. In a way, that would make the scene even sadder.
These four plays are centred around the way insults in ancient times demanded revenge, often embroiling families (or, in the case of the Trojan War, whole countries) in situations where blood was inevitably shed. It was easy to blame the gods, but Euripides' view was that men should help themselves - not an easy thing to do if you've got a goddess with a grudge on your back, though.
When reading these plays, for the first time, it was surprising how many names and events (and even plots) were familiar (as were the plays in Sophocles' Oedipus trilogy which I read earlier in the year). The legends of Ancient Greece were not only relevant at the time of their performance, but also today; for anyone of European or Anglo-Saxon heritage, these tales are part of our cultural background, and it's important to revisit these stories to see how to deal with adversity in life. Or not, as the case may be.
Now, I'm off to see a man about a dragon...