Homer, in book 5 of the Iliad, tells us that during his expedition against Neleus of Pylos (Poseidon's son), Heracles won battles against Poseidon and Apollo, and managed to wound Hera and Hades with his arrows.
He also killed Neleus and eleven of his twelve sons, including Periclymenus (an Argonaut and a shapeshifter). Citizens of Pylos that stood in his way suffered a similar fate.
All this, because Heracles felt Neleus had insulted him.
Now, Heracles wasn't known for running away from a fight. However, going into battle and slaughtering a city over an insult feels a bit out of character for the classical version of the legend. Furthermore, overcoming not one but four Olympians is simply too magnificent a feat. Some, including Pindar, are highly skeptical of the story:
For how could Heracles have wielded his club against the trident, when Poseidon took his stand to guard Pylos, and pressed him hard, and Phoebus pressed him hard, attacking with his silver bow; nor did Hades keep his staff unmoved, with which he leads mortal bodies down to the hollow path of the dead. My mouth, fling this story away from me! Since to speak evil of the gods is a hateful skill, and untimely boasting is in harmony with madness.
Was there a significant change in views about Heracles from Homeric times (around 850 BCE) to Pindar's time (c. 522 – c. 443 BC)? Was the Homeric version of Heracles a far more brutal hero than the classical version? And if so, have we identified other distinct points in the transformation of the myth?