The Fleimrut Awakening is the name given to the year the Yolus leyline beneath the Fleimrut Mountains tore open and did not close again. It is dated to 2500 SD. That date marks when the tear happened, not when the trouble ended, because the trouble has not ended. The fire-geysers that had always made the range dangerous erupted that year with a violence no one living had seen, and when the worst of it passed the seam underneath was wider than before and bleeding. It has been bleeding ever since.
The seam that will not close
Yolus is the fire layer of the Elemental Planes, and the leyline that carries it runs close under the surface in several places across the south. Beneath Tarkhetan it powers the Firemage Corps and feeds the Evertorch, and there it holds steady. At the Firefrost Hills, far to the south, it runs erratic for reasons of its own. The Fleimrut is a third case. The branch of the seam that surfaces here was never stable, and in 2500 SD it failed outright, opening into a standing breach between the mountains and the fire plane. The fault is in this stretch of the seam, not in the leyline as a whole. A shaper working fire in Tarkhetan would notice nothing wrong. Only here, on this one branch of the Yolus, does the wound stay open.
The world has seen this kind of tear before, larger. The World Fire of 10 BSD was the Yolus seam rupturing under a single overreaching shaper, and the fire it loosed glassed a whole country and set the calendar to zero. The Fleimrut Awakening is smaller, slower, and has no named cause. No paragon stood over it. The seam gave way where it had always been weakest. But unlike the World Fire's wound, which surges and gutters on its own schedule centuries later, the Fleimrut breach has stayed open. Things come through it.
A fire-geyser vent on the Fleimrut's middle slopes, between bleeds. The rim is glassed black and slick, fused by a heat that comes and goes. Down the throat the rock glows a steady orange that never flickers the way honest fire does, and the air above it bends. Nothing burns here now. Everything is warm to the touch, and warmer the lower you reach.
A crisis that comes in waves
What comes through is fire with shape and will. Emberlords and Cinder Swarms pour out of the vents, elementals drawn off Yolus through the open seam, and they do not go back down it. They spread into the range and have to be fought or fled. Most of the time the bleed is slow. A vent throws up a Cinder Swarm, a high valley fills with elemental fire for a season, a caravan road closes and later reopens. The mountains carry this the way a coast carries weather, as the standing condition of the place.
Then, on no schedule anyone has charted, the seam convulses. A flare-up of the kind that opened the breach sends Emberlords down out of the heights in numbers, burns out whole stretches of the lower slopes, and reaches the settled edges of the range before it spends itself. These larger crises are what keep the Awakening from settling into mere background hazard. Between them the Fleimrut is only deadly. During them it is a front.
You learn the mountain's moods or you don't come back. A smoking vent is nothing. A vent gone quiet that roared last week, that is the one to run from. The Fleimrut holds its breath before it wakes. — a route-warden's rule, the southern Fleimrut roads
Who lives with it
The fire-trolls of the Fleimrut are the one people who live inside the crisis and do not simply lose to it. Their long symbiosis with the range's fire elementals, told in their own account, became far more useful after the Awakening and far more dangerous to everyone around them. A fire-troll clan that can treat with what climbs out of a vent is the nearest thing the region has to a defense against the breach, and the nearest thing to a weapon aimed at its neighbors. Both readings are correct, which is why the clans are courted and feared in equal measure.
For the Tarkhon Empire, whose territory takes in the range, the Awakening is a breach it can neither close nor afford to let spread. The empire's fire-shaping strength sits at Tarkhetan, hundreds of miles north on a seam that behaves, and that strength does not travel. So the Fleimrut is held at arm's length: watched, skirted, and left to the fire-trolls and the route-wardens who have made their peace with a mountain range that is also a wound.