The smoke was making his thoughts slow and blur together, and suddenly he found himself dependant on the sting of his lungs, the crippling ache in his side. By focusing on it, he could fight off the feeling of fatigue eating at his every conscious thought.
But if anything was going to stop him, it was the heat. Unrelenting in its pursuit, the flames were nearly licking his heels, and the heat radiating from the red and orange wall was sapping his energy out of him. He could almost feel it leaving him, imagined the fire consuming it behind him to push itself on. Getting stronger and stronger as he grew weaker and weaker. And the more it grew the hungrier it became, demanding more and more of him.
The trees swayed and blurred before him, and his sense of balance was all but gone, more stumbling than sprinting in his futile efforts to put distance between him and his certain death.
He tried concentrating on the ache in his side, but the trees kept swaying. He looked straight down at the ground. The ground was stable. It wasn't shaking or spinning or blurring. He looked up to the trees to see them flicker like a flame themselves. The tree before him looked like thousands of arms reaching toward the sky, trying to clasp a cloud with one wooden finger reaching toward the blue beyond. That's when the first tree vanished. It left without so much as a sound, just dissolved into a bit of smoke that rose into the air, past where it's branches had been, past even where they were reaching for, and farther and farther until he couldn't see it anymore.
He saw several more puffs of smoke rising, and just the fact that he could see that far away was enough to tell him the foliage had thinned significantly. The tables were starting to turn; the fire was having a harder time advancing on him with less to burn, and as the branches receded it was easier for him to run through. His head was clearing, his will returning.
The puffs of smoke continued to drift upwards, signaling another obstacle gone. He'd just convinced himself he might actually make it, when he saw what he thought to be another ravine in front of him. But this time, there was no other side to jump to. It was a cliff.