A/N: I'm going to do the entirety of Death Magnetic at this rate, so I'll try and go for more early Metallica next time since I haven't done much of that yet. This song is actually about hounds that hunt people in nightmares, but I think it works well for hellhounds too.
All Nightmare Long
The moment he sees Ruby's eyes turn white, Dean knows it's over. This final scrap of hope, that maybe by killing Lilith they can void his deal and let him evade Hell, is torn away and ripped to pieces, just like he will be in a few short moments. As the door opens he can hear Sam crying out, pinned to the wall, and he wants to say something to reassure him and promise him it'll be okay, but he can't because the lies won't come out of his mouth when he's so freaking scared. He knows what's about to happen, and he's praying that somehow Sam will escape and survive this, but he knows that Lilith won't let that happen. The deal will all have been for nothing and Sammy will die anyway, just a pawn in a demon's game, and there's nothing Dean can do to save his brother. That thought terrifies him more than the realisation that there's nothing he can do to save himself.
Time seems to have slowed, but he still can't turn or move enough to get away. Horrific images twist around him, hallucinations brought on by the proximity of the hellhounds, and he knows death is imminent. They're still barking as they charge past the threshold, baying for his blood and the taste of his flesh between their teeth, and an instant later they're on him and dragging him roughly to the floor. He tries to get up, to run, but Lilith's too strong and he's still pinned to the ground, feeling their hot, sulfur-tainted breath on his face. He still can't see them properly, but that only amplifies his terror in his final moment without pain. The things that have hunted him down without mercy have now found their prey.
Teeth and claws sink into soft flesh, tearing at skin and brutally ripping tissue and muscle apart. Screams of agony join the chorus of ravenous growls as blood spatters everywhere. Dean's isn't the only voice screaming as the hounds tear into him, but he's in too much pain to hear Sam's cries above the sound of the barking and his own body being torn to shreds. He doesn't know at what point his brain finally shuts down to spare him the agony, but eventually, somehow, all the screaming and the crunching and the gnashing fades to silence, and then he's falling. Falling through an endless blackness, that's blissfully quiet and free from pain.
It's cold at first, pleasantly soothing after the burning agony he just experienced, but as he falls further Dean can feel the heat rising. As it does so he begins to fall even faster, until it begins to scorch him, and then he wants to cry out again just as he suddenly stops, his motion halted and a sharp jolt of agony tearing through his wrists, calves and shoulders. The shock stops him from screaming, but he can feel fear building in his chest as forks of lightning flash around him, illuminating the ropes and hooks by which he's now suspended. The stench of sulfur is overpowering, and it's as though he can almost choke on it, like the fumes from the inferno that's raging below him.
So this must be Hell.
His eyes flicker around, taking in the nightmare he's now trapped in, and as he does so an overpowering, unbearable wave of fear washes over him. In that moment he wishes he could take it back. He doesn't want to be here, wishes he hadn't made the deal, and just wants somebody to come and save him. Please someone save him. Please Sam…
But Sammy isn't coming. He knows that. He knows this is forever now, and tears flood his eyes and threaten to spill over as he realises just what he's in for. The pain he'd felt at the claws of the hellhounds was just the beginning, and then the tears finally begin to flow as he wonders what further horrors are to come.