A body of crystal and limbs and tentacles, the theletos is an aeon responsible for freedom and fate (and thus slavery and prophecy as well). Mechanically, it’s kind of fun: the theletos’s wreath of fate ability forces players to choose between the staggered condition or lousy dice rolls, while its spell-like abilities are a range of compulsions, charms, and curses that will be either comic or tear-your-hair-out frustrating, depending on your group’s dynamic. Thematically, though, the aeon is tricky, because when should the GM deploy it?
Here’s why I ask this: PCs fighting a bythos (CR 16) or pleroma (CR 20) are already probably fighting for big stakes; adding a living concept of duality to the foe roster isn’t a big deal. But the theletos is only CR 7…making it far easier to incorporate into most campaigns…but you don’t want one showing up every time the party paladin frees a handful of slaves.
I suppose the key is to save the theletos for certain crisis points—when a prophet reveals too much about a certain subject, or when the PCs’ actions could spark a rebellion or abolition rather than just a few more or less freed slaves. Theletos interference could also explain why slavery, serfdom, or fortunetelling are so entrenched in certain areas. PCs devoted to powers of balance, neutrality, or order might even be compelled by their faith or their divine patrons to aid a theletos—even if that means temporarily supporting slavery or killing prophets—which could be an interesting moral challenge for the right (read: mature and thoughtful) party.
Adventurers help azer slaves rebel against their overseers, who belong to a more powerful azer clan. But when the slaves begin to talk of forming a democracy, the adventurers find their efforts undermined by a theletos determined to preserve the fire-dwarf custom of slavery.
The Prophet Plague slays soothsayer after soothsayer, all of whom die with blue-white fire and prophecies streaming from their lips. Clearly some greater plan is afoot, because attempts to save the affected seers are met with theletos opposition.
A cluster of xorns regards a theletos as some kind of divine emissary. Sensing an opportunity, the theletos harnesses the xorns to help slaves tunnel to freedom. But neither the theletos nor the xorns care that these tunnels will cause an entire mountainside to avalanche, so it is up to a local ranger and some adventurers to find a better escape route.
—Pathfinder Bestiary 2 14
The relationship of azers to slavery has interested me for a long time; see more here.