There are a multitude of ways to burn in Hell. Tonight it's lava, flowing inexorably toward where Dean's impaled on the pit's version of volcanic rock. He screams as it flows over his feet, melting flesh, searing bones, stops when it fills his mouth.
Gotta cool you down, man, you're burning up, and boiling water is hissing off his immolated flesh. He feels hands, lips, Sam, and pulls away, horrified. Sam's flesh should be seared, blistered from touching Dean, but it's not.
Sam's shivering, cold water, and Dean doesn't feel it, feels nothing but hellfire burning endlessly under his skin.