Castiel is human, alive and living in the bunker with Sam and Dean. Two of those facts make him incredibly happy; one feels like utter failure. Cas cant heal anyone, read minds, fly or anything else that made him useful to the Winchesters. He's not even helpful on hunts, stumbling over and moving slowly so that he's more of a hindrance than a help. He almost got Dean hurt when the hunter had tackled him to the ground just before the werewolf they were hunting could side swipe Cas. On the ride home, Dean cheerfully offered him shotgun and Sam patted him on the shoulder like he was a small frightened child that needed encouragement. In a way, he knew he was and the truth of that made him feel pathetic. He said 'That's ok' and slid into the back, desperate for the familiarity and safety of the bunker and his bedroom where he could hide and try to deal with the maddening continual flux of his human emotions.

'It's ok you know, Cas, it was your first hunt as a human. You'll get better, won't he, Sam?' Dean had said while watching Cas in his rear view mirror, a false smile plastered across his face like he was trying to convince himself instead of Castiel. Shrugging his shoulders and making a non-committal sound, Cas sinks back into the safe shadows of the Impala and tries to stop his hands from shaking, ignoring Dean's concerned glances and Sam's attempt to encourage him.

Once they return to the bunker, he tells the boys that he'll stay in there for now and do research, catalogue the objects in the archives, translate old texts; he'll help in that way. Kevin's back living with mother since the boys saved her from Crowley so Cas has taken over his old bedroom. Much to his relief, Dean and Sam have decided to take it slow when it comes to the hunting, easier cases, not too far away, as Sam is still recovering from the trials. Sam had had to convince Dean to let him come along on the werewolf hunt, something for which Castiel was eternally grateful. He might've got Dean killed.

Cas did what he could to fix Sam with the last of his Grace that Metatron hadn't been able to capture but the hunter was still moving slower than normal, his cheeks hollow and purple shadows set deep beneath his eyes. Dean was treating his brother with more patience and care than usual and, despite his refusals and gentle mocking, Sam seems grateful to be given the chance to convalesce. Cas knew that soon the men would get fidgety, restless in the ways that hunters do and the thought of them, Dean especially, going out and risking their lives when Cas was powerless to heal their injuries filled him with an uncomfortable knot of dread in his stomach and an unsteady rhythm in his heart. He found that working tirelessly to find healing spells, powerful wards, creatures weaknesses, anything he can to help the hunter with their mission made him feel calmer, more in control of these new emotions and anxieties.

'That'd be great, Cas, saves me from doing the boring stuff,' Dean tells him as he claps his hand on Cas's shoulders and gives him that beautiful smile that makes Cas's chest swell and the intriguing but confusing flesh between his thighs twitch and pulse.

That is another thing; carnal desires, while not entirely unfamiliar given his secret obsession with Dean Winchester, are much easier to ignore when you are an angel. Angels do have sex, no matter what Sam and Dean may think, but not in the same physical way that humans do; all that rubbing and sweating and moaning that Cas has witnessed from porn (he may have watched more than just the pizza man) and humans as he watched over humanity for millennia never seemed particularly interesting or exciting ('Repetition' as he once told Kevin) until he met acquired his vessel, now his body, and met Dean. Whereas human sex seems to be mostly about the physical, angel sex is more an entwining of Grace, a metaphysical connection. Interesting, yes, but Castiel never found any of the other angels intriguing or adorably exasperating like he finds Dean. And now, being human, he's struggling to control and understand the overwhelming aches and throbs of arousal that pulse through him in Dean's presence.

Eating is very difficult too. An urge that is so natural to humans, and adored by Dean, is perplexing and frightening to Cas. When he had consumed hundreds of burgers because of Famine's influence on Jimmy, once the urge had passed, Cas had simply removed the food from his body using his 'angel mojo' as Dean calls it and that was that. The human version of this process is… different. Disgusting, actually. The first time it happened, Cas found himself close to losing the most recently ingested food from his mouth and the resulting sensation was of searing stomach cramps that left him bent double on the toilet and feeling weak, pathetic.

He tries to get used to it, he really does, taking books into the bathroom with him or playing games on the phone that Dean gave him and showed him how to use ('No, Cas, you have to push on the icon to make it work, not just randomly jab at it.') but he still felt sick at the more unpleasant procedures at the human body so he decides that the logical step to stopping this from happening is to stop eating. Simple.

It's surprisingly easy and immediately makes Cas feel better, more like himself. He passes on dinner one night (steak and potatoes that Dean plows into with much gusto while Sam slowly pecks away, his plate piled with plenty of vegetables and a smaller steak that Dean called 'girl-sized' provoking one of Sam's so called bitch faces where his eyebrows draw together, the skin between whirling into a rounded pucker and his lips following suit) citing a stomach ache as the cause for his disinterest. Sam offers up some possible remedies that he can procure but Cas politely waves the offer away with a smile and goes back to his room to continue cataloguing and repairing various archive files and objects, happy to be immersed in a task that will be helpful to the Winchesters.

The next day, Sam catches wind of a possible poltergeist near to the Kentucky-Missouri border that's targeting children so the brothers pack up and get ready to go.

'We should only be gone overnight, two days max. You gonna be ok on your own here?' Dean asked him as he packed up his bag, filling it with rock salt loaded shotguns, holy water, the demon knife and anything else he thought they may need. Castiel saw the first aid kit go in and had to twist his mouth in order to keep the wave of nausea at bay. He tried to school his features into something more neutral but Dean saw his expression and his eyebrows drew together in a worried expression. 'Hey, Cas, you ok? I mean, Sam can stay with you and I can take this one on my own-'

'No, no, it's fine Dean. Just… be careful, please.' Castiel pulled his bottom lip into his mouth, wet it then let it slip out through his teeth. Dean stared at him strangely for a moment then the jovial mask was back and he was telling Cas to help himself to the beer in the fridge and calling for Sam to get his ass shifting.

A few minutes later and the boys are gone, leaving Cas alone in the silence of the bunker. For a moment Cas thinks about having a beer and watching some television or trying to learn more about computers but instead he goes back to his room, shuts the door and continues to work through the huge piles of yellowing files, sorting them into categories and making notes on anything that could be useful, filling book after book with notes on wendigos, djinns, demons, vampires. Plotting out all possible means of execution, weaknesses, general lore; the rigidity of the process is soothing to him and he finds himself getting lost in a blur of lists, graphs and legends. He doesn't eat or his room again until he hears Sam and Dean return. The last time he ate anything was four days ago and his stomach is aching, clenching and throbbing with a hunger so desperate Cas has nothing to compare it to. It gnaws and claws at him and, when the smell of takeout food hits his nostrils, the twist of his gut makes him gasp and bend over, his eyes watering at the pain. Being sure to drink plenty of cold water (urinating isn't nearly so frightening), Cas imagines it filling him in order to soothe his stomach but soon enough even that won't control the searing cramps. But he won't give in. This hurt, this need, it makes him feel focussed, in control of the alien wants and urges that crash over him like waves. The pain gives him something to cling to so he doesn't drown. He has to have this or else he has nothing; he needs to be in control.

That night he excuses himself from eating, stating that he ate earlier in the day. Cas is pleased when neither Winchester says anything or looks suspicious as he sits with them and sips ice cold water, enjoying the crunch of the ice between his teeth. Cas swallows the ice in lumps, the density of it filling him up, the cold purifying and deadening his insides as it goes down. He decides that munching on ice is a great trick and hums happily as it numbs the inside of his desperate stomach.

'Dude, you're gonna crack your teeth and have to discover the awesome world of toothache. Trust me, nothing compares to having some masked bastard drilling into your gums.' Dean winks at him and takes another bite of his burrito, causing lumps of onion and tomato to drop out and plop onto the table in front of him. This close, with his new-found fascination and abhorrence of food, Castiel finally understands why Sam glares at Dean so much when he eats. Dean's a sloppy eater and constantly talks with his mouth full, getting food all over his fingers and sauce on his chin as he recounts the hunt to Cas with all the vigour of a man come back from a ten year war, Sam smiling and rolling his eyes as Dean gleefully exaggerates things, like how he leapt ten feet in the air to whack the ghost with an iron crowbar or how Sam, Sammy as Dean always calls him, was utterly useless with his lighter and almost caught fire.

'You're so full of crap, Dean! You were the one tripped over a gravestone and landed on your face.' Dean takes an extra huge bite then says 'Diversionary tactic, Sammy! You know nothing,' and grins as Sam screws his face up at Dean's stuffed mouth.

Castiel catches a whiff of burrito and sees the chewed up lumps of meat and plants, runny with some sort of white and red sauce and has to run back to his room, to his private bathroom, just managing to lock the door behind him before he vomits up the water in his stomach, retching uselessly on yellow bile as the sight, sounds and smells of food wash over him again and again, the images torturous inside his head.

'Cas? Hey, you ok?' Cas hears Dean yell through the door, 'Open up, man, we need to see if you're ok.'

'Have you got a stomach bug, Cas? Coz I can get you something for it,' Sam calls through the door as someone, probably Dean, rattles the handle.

Cas wipes his mouth, scared that Dean will notice the lack of food in his vomit, and stands up to try to open the lock but his head spins and everything strobes white and black and then there's just darkness.