AH. scary. seriously, this is like lovecraft or something. This is so awesome.... I honestly didn't expect to be scared at all (written stuff hardly ever frightens me) but congrats, you managed it, heh. Captured the whole waking in the middle of the night thing and wondering what that strange noise was, something that happens to me a lot. I know exactly how Dean feels.

Love, love that you used the rats. You've reinvented the rat for me. It's now a swarm.

  It started out rather well, I was giggly at Dean cowering, and then... the giggling stopped. It reminded me alot of Hellsing (I don't know if you know it, anime, but it's a good reminder, because Hellsing is fantastic).  

The imagery is so intense, I can just see everything. ...cries out as his hands sink into a yielding mass...  I love that bit. The chitinous horde is so vivid throughout... just everywhere...

...barely remembering to turn the knife in his hand away in time to avoid cutting his own throat... God, that's horrible, that really captures the panic of it, I think that's the moment that first scared me, made it real, imagine being so scared you might do that...

 And you had Dean wake up, without making it just another deus ex, creating an incredibly creepy ending. I hope Dean can handle it, 'cause if I had a dream like this I'd need lots of padding and pills, I think.