Some stories have Zeus (sometimes Hermes, sometimes Athena) actively instigating the Hera/Herakles feud by tricking Hera into breastfeeding Herakles and he bites her nipple off and her breast milk streaks the sky...
And that's how the Milky Way got it's name.
(What was my point, oh yeah,) The Gods where created to teach stories and their rolls/personalities/powers changed from story to story to fit the narrative. Mileage on how much they change does very. I mean, Athena is all over the place while Zeus is relatively consistent by comparison.
Historia is just another story where the gods are changed to fit the narrative, and even still, most of them aren't changed that much personality wise. You can find a story or two where each god has been merciful and you can find a story where each god has been wrathful.