A Scarlet Thirst

Thimunai, a godling of minor power, more of a spirit, with only one temple and three priests, was the patron deity of the mountain hamlet of Harvan. The locals revered her with song and prayer, offerings of honey and milk, and once a year, on the winter soltice, a piglet. Thimunai loved her mountain valley, and let pure springs bubble forth from the mountains, blessed the terraced fields and the children that were born, and gifted everyone with a small boon when he was born - such as a musical talent, a knack for understanding feelings of others, or the ability to warm loved ones gathered around you in the cold winter nights when the blizzard howled, its teeth ripping into anyone caught outside.

One such winter, when the cold was such that trees splintered and deer froze in the midst of a stride, the ogres came down from the mountains, driven out by the snows, hungry and desperate. And they found the village.
Screams echoed through the night as doors were smashed in, the villagers dragged out to be devoured on the spot or to be saved for a later treat. The men of the hamlet were certainly no weaklings, but, armed with but tools, no match for the rampaging beasts. The villagers despaired, and Thimunai cried tears of despair and terror, for she was powerless to stop the killing.
Then, it happened. A farmer, seeing his daughters being taken away, and surrounded by the ogres, thrust his kitchen knife into his chest, screaming at the top of his lungs: 'With my free will, and without hesitation, I give my life to you, Thimunai, my soul, my spirit, my very existence I dissolve into thee, my lady. Save our people!'
Thimunai felt a surge unlike anything she ever felt before, filled with all the power the gods must have invested into the creation of a human soul, which, willingly undone, once and forever, seeped into her.
The villagers stood amazed as the leader of the ogres burst into flame, and fell to the ground, charred, as if he has touched the sun. And Thimunai manifested, not as the flower-clad girl a stray woodsman might see dancing in the woods, but a winged embodiment of fury, eyes radiant, a trail of solar flame behind her, a blade of leaping sunfire held up high. And she lashed out, at all those who dared to wrong her people, searing the raider one by one, chasing them through the waist-high snow and beheading them, and ... enjoying the chase, enjoying the feeling of power over life and death...

And SHE thought.

The villagers, rejoiced at their unexpected salvation, thanked in prayer, and cuddled up in their homes to wait for spring.

And SHE thought.

When the rays of sun restored to its glory finally melted the snow, the villagers thanked their patron again, and ... several youngsters fell down in seizures, their voices merged into one, that calledtho the shocked gathering: 'I saved you, and it is I, your lady, who will be praised as the farmer praised me. Willingly. Heed my words, and prosper. Fail to worship me thus, and I may not be able to save you again.'
The people were befuddled and did not know what to do, until a small girl spoke: 'Mother, father, do not fear, for I will go. Take me, lady, to protect my parents and all nice people here.' And she leapt into a crevice, her body breaking on the rocks deep below.
One of the priests, shocked by this and shaken to the core, left the village right then. The other two remained.

That summer, a contingent of soldiers from the town of Hyrkul, in the foothills of the mountains, came, following a prospector, and meant to enslave the farmers to mine a newly discovered gold vein. None of them lived to see the sunset, their burned remains fertilized the soil, their blood made the streams run red, and their screams filled the air. And Thimunai liked it.
A few weeks later, the town of Hyrkul faced a truly strange sight - a sole priest, walking up to the gate, and demanding the unconditional surrender and the worshipping of an unknown god. The town council came, and when they heard the old man's demands, they laughed and ordered him beaten and chased out of town. The first one who lifted his hand against the priest was consumed with flame so hot that it was white. The second one as well, and then, the whole ground under the councilmen melt into a puddle of fire, and they burnt like bacon in a pan, their voices but the squealing of a slaughtered pig, their eyes bubbling and flowing from their sockets.
No one else dared to resist.

This was two years ago, and two other towns fell. The children born started to recieve different gift as well - great resilience or strength, or the lack of a need to sleep. Many of them seem to have magical talent... and Thimunai hungers.

How could the players get involved? And what could they do?
*One possibility is that the priest who left before it all started wants them to go and reson with his goddess, as she will not listen to him for abandoning her.
*The PCs could be members of the new faith, assigned missions by the priesthood, and facing moral dilemmas.
*They could come from the outside, trying to defeat the new power (good luck, then :D)
*They could be priests of a church that was worshipped in the valleys before this all started.

It is hard to persuade someone to sacrifice himself willingly, at least in the beginning stages the religion is in - the next generation would take it matter-of-factly though. Only a sicere sacrifice will feed Thimunai the way she has begun to like it.

The godling does not have the kind of power the major ones have, but she does not have to watch that many worshippers and her power is focused in one place, not spead all over the lands, and she is not (yet) subject to many of the laws the major gods must oblige to.
What does prevent one of the major deitites from squishing her? Perhaps one of the aforementioned laws, or maybe another god is amused by her, and keeps the others from interfering?