At least three varying histories of Pan exist. The first has it that he's the son of Uranus, created when the old Sky's blood spattered the earth, and having grown up in the mountains and woods near the ocean. The second claims that he's Zeus' son from an unmarried wife, while the third attributes his parentage to Hermes. Truth is, though, Pan is just a force of nature - both generous and destructive - and it doesn't matter where he came from.
Pan lives on the outer edges of the realm, and doesn't spend much time on Mount Olympus. 'Course, the infrequency of his visits makes them that much more special. At such times, he's spied wandering the mountain (Pan himself, not an avatar), playing on the pipes traded to him by Apollo for services unknown. He's a great favorite among the satyrs and centaurs because he's passion unbridled. Pan pursues his desires avidly, and those who follow him seek to emulate him as best as they can.
Still, lurking beneath that leering face Pan chooses to wear is a deep font of wisdom and peace. He's given himself over to his passions, but he did it with the full knowledge of what he was doing, and he's accepted what he is and what he does.
Pan's favorite power in the pantheon is Hermes, for the two find common ground in mischief-making. Dionysus is a close second; he and Pan are top-shelf carousers, and they've found friendship at the bottom of many jugs of wine. The rest of the pantheon lets the god of passion prowl as he will, welcoming his presence - although they're glad his visits are rare. Pan's revels are exhausting, even for the powers
His proxy is a satyr called Marsyas, a brash creature who's come within an inch of being struck dead by various powers throughout his career. That's because Marsyas' main ability is the gift of satire, a cutting with that can both enrage and embarrass its target. That's not much of a gift, to be sure, but it's one the proxy uses to great effect whet he knows that he's beyond retribution.