Shane had managed to pull himself up to sit, and was summoning the energy to get to standing when he looked up and saw Aaron, there. His first reaction was a deeper level of shock and frustration--he was starting to hallucinate, not a good sign--before he realized that Aaron was, in fact, real.
His eyes were glazed, and he felt slightly outside his own body. Though he knew intellectually that it didn't really matter whether he lived or died, something else had locked into place and was keeping him from simply laying down and bleeding out. It was there behind his eyes, a desperate, animal intent on survival.
"Get the fuck out of here," he growled, with enough of a hoarse rumble behind it to give it weight despite how pale and clearly injured he was. There were claws on his hands and a hint of sharp teeth in his mouth. He didn't have to try very hard to look like a nightmare. If this kid had any sense, he would run far, far away and pretend this had all been a dream, since if he decided to be well meaning and call 911, he was fucked. Piper possibly moreso.