Moments of unadulterated peace were few and far between in Purgatory.
When the off chance the monsters adamant to rip them apart slowed their pursuit, Dean took that time to sink into blissful oblivion wherever he could; the conditions were never great, but what could he have expected in this sinister circus of lost, bloodthirsty souls? (A majority of which Dean was almost sure he'd sent packing into this wasteland himself over the years.)
The only speck of salvation Dean had in Purgatory - the one thing keeping him sane - was Cas, but even then he wasn't sure Castiel would stick around.
Purgatory, Dean found, liked the prey on his mind.
Upon arrival, Dean remembered feeling himself drowning in fear when he'd discovered himself alone in the clearing. He'd felt the bile rise in his throat when the scratching, the rustling, growling, the inhuman cackling had sounded around him and felt his blood run cold when he thought: this is it. I'm going to die. He remembered running as hard and for as long as he could through the trees, avoiding every narrow, glowing pair of eyes peering at him hungrily from the underbrush until he ran smack into Castiel. Purgatory seemed to have had its fun. Dean had been alone; he'd been scared; he'd lived through one fear, so they'd given him back his Angel until they could pick out another trauma from his sea of memories to toy with. So far, it had only given illusions; hallucinations of blood, of fire, of every little insecurity, but they hadn't broken him yet.
But that's not to say they hadn't worn him down, and consequentially Dean had developed a habit.
Castiel didn't think much of it at first, thinking it was just a one-off type of thing. What he hadn't expected was for it to happen every time they found a place to rest. He didn't mind – of course he wouldn't – but he was curious. Both Dean and Castiel had lost track of time in Purgatory, and neither sought to care as long as they could stop for a while – take a breather, calm their nerves and just relax.
This time, their solace came to them in the form of a cavern. It was cramped, damp and cold, but they'd had worse and as far as they could tell they had neither been followed nor could they be seen from the entrance. Dean had joked they needn't worry about monsters tracking them by scent, because thus far they'd rolled through enough dirt to be indistinguishable from the forest floor, and Castiel had hoped he was right. Thankfully so far they hadn't been attacked while they rested, but that didn't mean they could let their guard down.
"Rest" had taken on the definition of Dean catching up with as much sleep as they could manage while Castiel kept watch. Cas didn't need to sleep, so instead he took up his position sitting in front of his charge and trained his eyes on the gaping cave mouth. They'd hunkered down in the pitch black at the tail-end of the cave, where the light didn't reach, so they considered themselves at an advantage; they knew that to their backs was a small exit just waiting for them to run through if anything unwelcome were to pop in for a visit.
During these small hours of peace was when Dean's newly-formed habit reared its head.
Sitting as he normally would, Castiel had his back to Dean who had lain down within arm's length of him, curled up in a ball against the cold. Castiel had offered his trench-coat to him multiple times, noticing how the chill and damp could be both risky to the hunter's health and compromising to his sleep, but each time Dean had refused with a look of incredulity on his face. "Dude, no, I can handle it." He'd said, holding up his palms against the fabric and pushing it away from him each time Castiel had held it out in offering. It had irritated Castiel somewhat because he thought Dean was just being stubborn, but the true reason Dean didn't want Castiel to part with his trench-coat was evident every time Dean was barely coherent to his surroundings and falling into a welcome onset of drowsiness. Hearing a shuffling behind him, Castiel cracked a small knowing smile as he felt a small tug at his back, the tan trench-coat weighing down on his shoulders as Dean snaked two fingers through one of the belt loops as he'd become accustomed to doing every time he was too far gone to realise.
Curling his fingers into a fist and clinging on to the small piece of material, having found his sense of security, Dean murmured just quiet enough he was confident Castiel wouldn't hear.
Castiel always heard the words Dean uttered, however; always heard the lapse in bravado and the concern when he whispered: "Don't disappear."