Joe Bob's condition

Had Lindsey asked Stolenberg, he would have received a cryptic answer: "Because I am the Surgeon General."

But the Surgeon General was on vacation. Whenever he was faced with a situation he couldn't handle or one that simply bored him— like the one he was in right now; he hated riding buses, and always had since he was a kid living in Waco and had to ride the school bus for nearly two hours every day—Karl simply unplugged his mind and went into a state akin to Dream Time as practiced by Australian aborigines, only he called it walking the Dead Highway.

He was on that Highway as Lindsey looked at him, oblivious to the black man's attention. Oblivious, in fact, to everything around him. Here, on this barren stretch of Right Brain Freeway, he was safe so long as he stayed on the sunburned tarmac. If he strayed off and went wandering the wasteland (and sometimes he was tempted), he risked falling prey to the dust devils and sand demons that lived there, or the clutching, desperate arms of his victims, who writhed in their shallow graves at the side of the tarmac.

...

Joe Bob was filled with sadness, fear, and a terrifying sense of inevitability. He knew he wasn't really six feet tall, wasn't in fact really real; he was an adjunct of the dreamworld, an essence that lived because Karl, his master, wanted him to live, and after he'd been splattered by that truck and Karl had buried him, his little armadillo soul had gone to the Other Place, which Karl called the Dead Highway, and he'd wandered the tarmac, rolled in the scrub, rooted around in the arroyo, neither in armadillo Heaven nor Hell.

But now his time in dream purgatory was nearly over. He'd be leaving soon for parts unknown, would ramble down a different highway alone. He was sad. And scared.

Joe Bob knew he was going to die.