As mentioned before, what’s great about mephits is that they have personality—too much personality. Also, Todd Stewart’s The Great Beyond blew the possibilities for mephits wide open with his azer-enslaving fire mephit theocracy. There’s no reason the other mephits can’t think as grandly…
Fire mephit inquisitors have a difficult time interrogating apostates—their victims usually being as damage-resistant and immune to fire as they are. Some experiment with dabbling with cold magic, but since that might also be construed a heresy, most just hope to torture travelers from the Prime Plane—adventuring parties especially.
When they deign to notice humanoids, ice mephits often reveal themselves to be sadists. Normally others are beneath their notice, but they do find warm-blooded creatures’ reactions to cold intriguing, especially when augmented by their sickening breath weapons and spell-like abilities.
Murt the magma mephit is unlike his peers; they are brutes, and he is a poet. What this means is that rather than trying to bully interlopers with fire, he bullies them with demands they critique his work. Then he bullies them with fire for being too critical.
—Pathfinder Bestiary 202–203