Castiel had been walking when he heard the first one. It was nervous, like the speaker wasn't sure who was tuning into this frequency and was thus self-conscious of themselves which the angel found ridiculous since they were in the wilds of purgatory and thought perhaps that such petty emotions would've been drowned out by the survival instinct. He thought wrong.
"Hey uh Cas?" Castiel stopped walking momentarily to listen to the voice, the strong undertones that he had become so well acquainted with. "Cas its Dean… but I mean you probably know that. Listen you wanna tell me where the fuck you are? It'd mean a lot, thanks." there was bitterness in there mixed with hurt, it was very readable. Castiel was used to Dean's prayers being short and to the point but this one was different. It wasn't a demand or a summoning, it was worry for him. He wasn't being prayed to because Dean needed him to do something for him rather like a nervous mother would check on her child repeatedly through the night. For confirmation something terrible hadn't happened.
Castiel's first instinct was to fly to Dean, like he did nearly every time there was a prayer. He had to halt and remind himself why he had separated from the hunter to begin with, for his own good. It was only for a little while and then he could get out, taking Dean with him. Castiel began walking again with little trouble, he reasoned out that in the end it would've been better for both he wasn't there endangering his life. Dean would thank him later.
The second one came the next night, it wasn't meant to be a prayer Castiel didn't think. He was sitting in a clearing, night was upon them and the angel sat perched on a felled tree, he had no use for a fire and was only stopping for a moment to recollect himself and reroute to ensure he got where he needed to go the quickest way possible. There were no words but he felt something deep in the pit of his stomach he knew automatically was second-hand emotion. Castiel did not feel these things on his own and so he aptly concluded it to be the Winchester. It was fear, deep seated and threatening to spill over in Dean's head. He was paranoid and Castiel hesitated as he stood, looking back the way he came as though he could maybe find some way to reassure Dean that he was going to be okay and they both would survive this. However he knew there was no way without drawing attention to himself and so with a deep breath Castiel set off walking into the trees again.
The third prayer was for luck, it wasn't even a coherent one, mumbled underneath his breath but still the angel heard. He was praying for luck that he would kill a deer, Castiel felt anxious for a moment, wondering if Dean was getting all he needed to eat and if he could help in any way without hurting the human. He knew the answer was no still and with a heavy heart he continued on moving towards his goal.
Four through seven were half hearted attempts to start conversation. These ones were much easier to ignore as Castiel found it to be just like ignoring Dean face to face when he wanted to discuss things the angel had no desire to join him in. It would start out as a prayer and devolve into a telling of all that had happened since Castiel left him. The angel learned he was travelling with a monster but they seemed to be working on some kind of understanding. Castiel was concerned as nothing in purgatory was to be trusted but believed Dean to be capable of making his own decisions and to be intelligent when choosing allies. The angel was lost and had bigger things to worry about at the moment.
Eight woke him from a daze at roughly two hours before sunrise. The angel had been staring blankly at a space for a few minutes attempting to figure out where exactly he was when he heard it loud and clear.
"Cas, listen I don't think you can hear me, I mean, I know you would've come by now-," Castiel winced slightly at the blind faith in the Winchester's words, the way his voice trembled just so. "But I thought I'd try again. Please, if you get this on your heavenly answering machine or whatever." The urge to go to him now pained him, the angel balled his hands into fists and began to walk, not caring where he was only that he had to reach his destination more so then ever.
Nine, ten, eleven, twelve… the succession grew more and more desperate at each turn, emotion no longer guarded, Castiel was subjected to the full brunt of the spectrum Dean was feeling. Anger, confusion, loneliness, abandonment. The list carried on and on and each prayer got longer and more detailed as to what Dean was willing to give up in order to see the angel just one minute longer. The man would beg and plead and still Castiel continued to walk, it was this task he dove into fully.
At night his heart would ache and had angels been able to cry Castiel was sure he would've been doing a lot of that activity recently. Every night it just got worse, the trenchcoated angel having to stop sometimes, so out of breathe was he from the hunter's sadness and depression from being abandoned in a strange place by a man he deemed a friend.
Number twenty three was when Castiel began to feel crippled. Dean's prayers weren't even prayers anymore, when the angel felt the connection it wasn't intentional. The only things he felt now were grief, drowning waves of grief that made him curl up in a ball on the floor of this godforsaken forest and have to wait for the feelings to pass. The Winchester had stopped speaking, it seemed now that he packaged up emotions and memories to fill the void where his spoken prayers should have gone. The feeling of grief was because Dean believed that Castiel was dead, he was in mourning.
The angel had to say his cause aloud now, if he wasn't constantly reminded he would've thrown everything away to go to Dean in the night and let him know that he was still there.
Prayer thirty two was when the grief died out replaced by a small amount of hope. Hope that perhaps he could get out of purgatory after all, Castiel was pleased that these intense feelings were being replaced by happier ones but his relief was short-lived as hope quickly turned to vengeance. Boiling hot like a burning iron, Dean's nature from what the angel saw through these segments sent to him, had truly been warped by purgatory. Castiel's biggest regret in all of his existence was leaving the Winchester alone in this wild.
By the forty fifth prayer, Dean was talking to him again. It sounded a lot more like the mumbling of an insane person than a real prayer and the angel was once again forced to tell himself this separation was for the better. "Why'd you leave me?" the voice asked him. Castiel turned his face away, ignoring was impossible however. "You just teleported away to wherever, leaving me to deal with this. I know you're not dead. You gotta be alive somewhere and I bet you can hear me. Why'd ya do it Cas?"
The angel could stand no more, he needed to be close to him, to let him know that this was not the case, that he had not abandoned him. The pure need to be near was making his vessel's heart beat faster.
Castiel walked twelve miles that night to keep his mind off of Dean. Even then he couldn't. In desperation at his situation, convinced he could not win, into the night Castiel spoke back, as though praying to Dean and hoping he could hear.
"I never left you."
Somewhere in the woods Dean Winchester woke in a cold sweat with the words of his angel echoing in his head.