Hercules is best known for his Labors, a series of seemingly impossible tasks deliberately imposed in the hope that they would indeed prove fatal. Accounts differ, but Hercules kills his wife Megara and their children while in the grip of a fit of madness inflicted by Hera, the hero's foe from before his birth, which resulted from the union of Zeus and Alcmene. To expiate the blood guilt of those murders, Hercules is sent to serve King Eurystheus and obey his orders. Since it would have been an equally serious crime to murder someone staying as a guest in your household, to rid himself of his ever more frightening "servant", Eurystheus sets Hercules after every local monster.
In his Second Labor, the monster is the Hydra of Lerna, a mass of poisonous snakes growing out of one body. Wherever one head was lopped off, two more would grow. Over additional obstacles created by Hera, and with the help of Athena and one of his nephews, who cauterized the neck stumps as fast as the hero removed the heads, the deed was accomplished. Hercules then very sensibly dipped his arrow heads in the toxic blood against future need.
Many years and adventures later, Hercules has a new wife, the young, beautiful, naïve Deianira (also Deianeira, Dejanira). When they come to a great river that runs across the road they need to take, Hercules knows that he can swim across, but that Deianira cannot, nor can he while bearing her. There is a sort of ferryman at the crossing, a centaur named Nessus. Other than Chiron "the good centaur", centaurs were not known for being well behaved. Once the girl was on his back, Nessus not only carried her across but tried to bear her away. Using his Hydra-poisoned arrows, Hercules brought Nessus down.
Exerting the last of his wiles, Nessus persuaded Deianira to take his blood soaked cloak, telling her that if Hercules wore it, he would always be faithful to her. Of course a time does come when she begins to have doubts and she presents the cloak to her spouse. Once on, the cloak cannot be removed and causes the hero to feel he is burning all over. He calls for a pyre to be built and throws himself on it.
The attempted abduction of Deianira was depicted by two artists whose works have furnished many cameo subjects. The earlier is a painting by Guido Reni.