Most giants owe their inspiration to Northern European folklore, but storm giants are clearly the heirs of Zeus, Poseidon, and the Titans of the Mediterranean. And those gods are good models for their behavior—benevolent to those under their control, and good…ish…when push comes to shove…but capricious, stormy-tempered (obviously), and very used to dictating the terms of any encounter.
Not familiar with Greek myths? Pretty much any authority figure in SpongeBob SquarePants will do the trick. King Neptune, anyone?
Of course the real reason to use storm giants isn’t for the giants themselves—it’s for their lairs. Even at CR 13 these are still near-mythic beings, so you can pretty much throw the usual building codes out the window. Cloud castles? Volcanic monasteries? Coral fortresses? Dragon-pulled levitating longships? Copper staff-studded lightning farms? Thunderclouds tethered in place by epic immovable rods? Yes to all of the above.
A party of adventurers limps through space, running dangerously low on oxygen after their voidjammer was beset by sun locusts. Their salvation is an asteroid with a small atmosphere of its own, courtesy of years of tending by a celestial storm giant and his skill with control weather. After years of hermitage, the giant finds that the company of adventurers sparks in him a desire for companionship…so he refuses to let them leave without leaving one member behind to wed.
Legend holds that the Endless Sea hides a continent that defies magical scrying or divination. A storm giant known only as Kamal (after the ancient navigational device) might know the truth; he is said to have mapped the entire globe from his floating castle. These days the castle does not move, tethered in place as it is by chains of adamantine and petrified sauropod spines. But Kamal does not entertain visitors, attacking all who approach with lightning and servitor fossil golems. His wrath is not due to his nature but to his concern for what his castle now guards: the grave of an undead hekatonkheires.
Alinus of the Deep always disdained the island fortresses and cliff castles of his peers. Instead, he travels the seas in a great turtle-shaped submersible known as the Natator. Currently, though, the vessel is grounded and under siege. Alinus and his triton allies face a lonely war against both a raiding party of demodands and an immature shoggoth that rebelled against the tarry outsiders’ control.
—Pathfinder Bestiary 152
For more on storm giants, Jason Nelson has a chapter in Giants Revisited.
Also, I completely forgot to tell you on Tuesday that if you’re looking for the stegosaurus and the stingray you can find them hiding in the Pteranodon and Manta Ray entries, respectively.