For the planet, see Jupiter
Oaths and promises were sworn on Jupiter (also known as Jove, Djeuspater, or Iuppiter Optimus Maximums) . He was the embodiment of law and order, and protector of the cosmos. The expression "By Jove!" remembers this aspect of his portfolio.
Jupiter is more than "just" the Roman equivalent of Zeus. He is the patron deity of Rome, and personification of the authority of the Empire. So, sure, he later incorporated everything that made up Zeus by way of Interpretatio Graeca, but he had his own identity on the side. He's a bit more of a war god than Zeus originally was, and likewise much more a god of bureaucracy and agriculture.
Oddly enough, you'll find very little in terms of myths of things Jupiter did that Zeus didn't. Even though the Romans worshiped Jupiter for centuries after the Greeks, they didn't add much at all to his body of myth. Part of the reason for this is that in the earliest days of Roman worship, the gods weren't personified at all. Jupiter, like all the other Roman gods, was either an abstract concept, or perhaps a particular rock that was invoked for it's mystic powers over the weather or harvest. It wasn't until the Romans had contact with the Greeks and Etruscans that they started building a body of tales about what the gods had done. Most of those tales were appropriated from the other mythologies. Rather than spinning new stories about Jupiter, they mostly just took old tales of Zeus and changed the name. So while he represents more, he doesn't do more. This is a little ironic, given that the Greeks so valued "thought" and the Romans valued "action".
In addition to Zeus, Jupiter also incorporated elements of sky gods from other cultures the Romans conquered or interacted with. He's associated with Tinia of Etruscan Mythology, Amon of Egyptian Mythology, Thor of Norse Mythology, Teshub of Anatolian Mythology and Sabazios of Phrygian Mythology, but the greek myths are the ones we (and the Romans) are most familiar with.
Jupiter is the father of Mars and Mercury. He is the sun of Saturn, and the husband of Juno, but these like all the rest of his relationships, are essentially inherited from Zeus. He gives his name to the planet Jupiter.
Game and Story Use
- Interpretatio Graeca can serve as a model for empires in your own campaign. Conquerors may subsume older cultures, just as Jupiter took on aspects of Zeus. Things can get pretty strange that way.
- Jupiter, God of Imperial Authority, is a lot more conservative figure than his oversexed Greek counterpart Zeus. In a campaign where both Gods actually exist as distinct entities, there may be some hard feelings between them. If they're the same individual, it may represent some mellowing and maturation as he grew over the centuries. These could be fun characterization angles for Zeus-as-NPC.