For years before meeting Dean and Sam Winchester, Castiel had understood the concept of sleep and rest, but never quite fully grasped the enormity of its importance in the well-being of all human beings… To him it seemed illogical that after only a few hours of activity, a human should need to lie down in a darkened room and basically fall unconscious for a portion of their day… it was such a waste of time. Angelic beings did not need sleep; it wasn't hardwired into their set up. They were overseers and warriors, guardians and messengers: none of which required the need to stop and rest. It was one of those subtle things which separated the angels from mankind; they did not weary, just as they did not grow old…

It had been Dean who had attempted to explain to Cas what being tired felt like, and how it presented in most people. He had described a heaviness, like a weight bearing down – starting inside the head and then slowly descending through the rest of the body, until the weight became overwhelming. Again, as Dean explained this, Castiel could not appreciate the fullness of what that meant – tiredness and heaviness were concepts he understood theoretically, but not in practical reality. He just had to put up with Sam, Dean and every other human being he came into contact with, needing sleep while he remained awake. When he had asked about what being asleep felt like, neither Sam or Dean could answer without stumbling – they both frowned, as though thinking, and then replied: nothing… Sleep was like nothingness, you didn't remember being asleep and you weren't aware of anything around you while you were asleep. Sometimes you had dreams – flashes of old memories, or storylines which invented themselves inside your imagination; but very rarely did people remember the details of their dreams, they often slipped away as you woke up.

The Winchesters were particularly interesting to watch while they were asleep – or Castiel thought this - as he discovered this the first time he watched over them in a run-down motel room in Illinois. Sam slept on his back, his face would twitch periodically and occasionally he would make a movement which suggested he was about to sit up and start talking. Dean, however, slept on his front – his head turned to one side, arm tucked underneath his pillow; it took Cas a while to realise that Dean's hand was gripped firmly around the handle of a knife under the pillow. Castiel came to the realisation that sleep wasn't going to be something he ever understood properly – but that was to change…

When Castiel fell, everything altered – no longer angelic, he fell prey to those things which he had never expected to need. He experienced hunger, and boredom – and exhaustion. The sensations were bizarre; he had to learn quickly how to distinguish between hunger and boredom, or physical tiredness and illness. Sometimes his mind felt like it was being clouded over by fog, which impaired his ability to make decisions, or think clearly – but that kind of tiredness wasn't always helped by resting; and sometimes he felt "tiredness" that was localised in one part of his body, and that was even more confusing! Out of all the new things he had to learn – learning to sleep and rest efficiently was the one that was causing him the most issues…

Sleep wasn't the blank nothingness that he had expected it to be; that he had been told it would feel like from Sam and Dean. It was flashes: of memories, of feelings, and sensations. He hadn't realised that dreams made up of memories didn't always consist of good memories… and his certainly didn't. He was persistently forced to relive and re-experience every bad memory: abandonment, distress, hatred, and worst of all – the sensation that he was falling. He often awoke from sleep, so agitated and panicky that going back to sleep was a practical impossibility – so when that happened Cas would get up and try to find some other way of occupying his restless and overwrought mind. He often ended up pacing the length of the motel room they were in, which often woke Dean up… Cas found out that when Dean didn't get sleep he became ratty, and at first he would snap at Cas for waking him up. But the more frequently this pattern became, the more Dean realised that shouting at Cas to go back to bed wasn't going to work. In fact, it was only making Cas worse…

Tonight Dean had reached the end of his tether, he needed to do something to end this cycle that Castiel had become trapped in. He was sitting in the motel chair – Sam was out doing research about the local area, the potential of a job luring him to find out more information; and Castiel was already in bed asleep, but all was not well… As Dean watched, Cas' chest began to rise and fall less evenly, he could hear Cas' breathing becoming more ragged. His face was twitching, and his fingers were curling into the bed sheets underneath him; very quickly his body convulsed and the noise of his breathing increased, sounding more and more agitated.

"Cas?" Dean started, wondering whether it was wise to wake up the distressed ex-angel in the middle of a dream. "Cas, buddy! Wake up!" He raised his voice.

Castiel sat bolt upright – he was drenched in a cold sweat, trembling from head to foot, panting heavily and felt sick to his stomach. For a few moments he was utterly disorientated and he whipped his head around before instinctively leaping out of bed; then he realised that it had been Dean who was calling him, and was not staring at him with a bemused expression as Cas struggled to gain control of his own breathing. Gaining control was a lot harder than it should be; he bent forwards gripping his hands above his knees. He couldn't seem to get the air past his throat, it was like it hit a blockage at the back of his mouth and a strange tingling sensation was spreading through his body – from his head down his arms and legs. He must have wobbled because suddenly Dean's hand had gripped on his upper arm and was pulling him back to sit on the edge of the bed.

"Cas… Cas! What's going on?" Dean asked, alerted suddenly to the possibility that Cas might pass out. He was really panicking – his face pale, sweat present on his forehead, his arms were shaking uncontrollably and his breathing was still very erratic.

"I – I – can't – I…" Cas tried to speak, to communicate how he was feeling, but to no avail; every word caught sharply in his throat and he was overwhelmed by a feeling of impending doom.

"Cas, take a deep breath, take a breath in – come on." Dean had perched next to Cas on the edge of the bed and was making direct eye contact with him; Dean tried to encourage Castiel by using himself as an example, taking deep breaths in and out. It seemed to work, as Cas followed in the same rhythm as Dean. It took a good five minutes before Cas had calmed down enough to be able to speak without panicking. "What's going on Cas?"

"Dream…" Castiel muttered, he had sunk his head into his, still quivering, hands.

"A dream did that?" Dean asked incredulously, Cas nodded feeling ashamed. "What the hell are you dreaming about:" There was a very short pause, in which, Cas raised his head so he was looking at Dean – apparently looking for signs whether he was being made fun of.

"Falling." He said simply, when he had concluded that Dean was being genuine. As an angel Castiel's expressions had been imperceptible; as a human he was as easy to read as an open book. Dean could see that Cas was on the verge of tears, he looked like a little kid in need of comfort.

Without thinking about it Dean stretched out his arm, placing it around Castiel's shoulder and pulling the trembling man towards him. Cas nestled his head in the crook of Dean's shoulder, he smelt musky and faintly like the leather of the impala and gunpowder – the scent was comforting… Cas could hear Dean's heart beating in his chest and it seemed to have an effect on the pounding of his own heart, it slowed down to the same speed as Dean's.

"It's okay, you're not falling anymore." Dean murmured and Cas felt the vibration from his voice box coursing through the rest of his body. "I won't let you." The arm around Castiel's shoulder had tightened slightly, it was a protective hold – Dean was protecting Cas.

"Thank you…" Castiel's voice came out as no more than a whisper.

"I mean it Cas, you know that, don't you?" Dean had suddenly relaxed his hold on Cas' shoulder and Cas drew back to look at Dean's face. "I won't let you fall…" The green eyes were full of compassion, of honesty and care as Dean stared into Cas' blue eyes. Cas nodded his head, but he couldn't tear his gaze away from Dean's eyes.

Then, Cas wasn't quite sure what happened, but his heart seemed to have increased in size and was pounding hard again, not out of panic – but something completely different. They stayed frozen for a few more seconds, then it happened: Dean had leant forwards, and their lips had met. Cas; lips were soft, the complete opposite of the rough stubble of Dean's mouth; Dean's hands had moved from Cas' shoulder and were cupping his chin. Cas felt like his whole body was tingling – he couldn't quite explain it, but he liked it. Dean's tongue brushed across his teeth and a shiver had shot up his spine – all the hairs on the back of his neck were on end.

"I… Dean…" Cas tried to speak once Dean had pulled back, but he was so tongue-tied that he couldn't say anything more than Dean's name.

"I won't let anything bad happen to you, alright Cas?" Dean stroked the side of Castiel's face lightly with the tips of his fingers; Cas nodded.

"Thank you." Cas reiterated. Dean seemed very calm – kissing Cas seemed to have had no change in his demeanour, whereas Cas felt like an explosion had occurred inside him.

"Do you think you'll be able to get back to sleep now?" Dean asked gently.

"I don't know…" Cas answered, biting his lip and looking down at his lap. Generally he didn't want to risk a repeat of a dream which would make him panic; normally he would have gotten up and found something else to occupy himself.

"Shall I help?" Dean offered. He shuffled up against the headboard of the bed, straddling his legs and pulling Cas up, so Cas' back was resting against his chest. Cas could feel Dean's heart beating in his back as he rested gently against his friend, and the rising and falling of Dean's chest was soothing. He was self-conscious that he might crush Dean, but Dean didn't seem to have that worry. "Lean back Cas, it's alright…" Cas' head fit neatly in the gap of Dean's collarbone, and Dean's thighs were straddling round the sides of Cas' legs. Once Castiel had settled against Dean in a position that the two of them were comfortable in, Dean stretched his right hand round and gently stroked the outside of Castiel's bare thigh. "Cas…?"

"Yes Dean?" Castiel responded breathily, the touch of Dean's fingers were creating thrills in his skin and causing him to gasp involuntarily.

"Are you alright with this?" He asked, "I don't want to do anything you're not comfortable with… will you stop me if you feel uncomfortable?"

"If you do, I will tell you." Castiel confirmed. "But you won't." Cas felt Dean's body stiffen for a second, and suddenly wondered whether he might have said the wrong thing.

"I won't what?" The tone of Dean's voice had become sharper.

"You won't make me feel uncomfortable." Cas explained, the muscles in Dean's chest relaxed again.

"I hope not." He whispered; the fingers stroking the side of Cas' legs were moving slowly, progressing their way closer to the inside of Cas' thigh – to the more sensitive skin near his groin. Dean dipped his head and gently kissed the exposed part of Castiel's neck, aware of the shiver of excitement that had run through Cas' body. "Do you like this?" He asked, Cas nodded his head. Dean's fingers were dangerously close to Cas' groin – the only barrier in between them was the boxers that Cas used as pyjamas. As Dean stroked, the effect of his touch became obvious: Cas could feel the blood rushing to his genitals, within moments he was becoming aroused – his cock visible, straining through the material of his underwear. Dean could see it too, and he lightly brushed over the material – teasing Castiel. Dean could hear Cas' breathing becoming heavier, he had involuntarily flexed his hips in an attempt to bring his hard cock in contact with Dean's fingers; but again Dean just ghosted over Cas' crotch – this time eliciting a vocal response from Cas:

"Dean!" Cas moaned, pushing his hips up again – this was perfect, it was better than Dean could have ever imagined… "Dean, please…!"

"You want me to touch you?" Dean asked softly, his low voice arousing Cas even more.

"Please Dean, please…" He begged, his breathing ragged and his body shaking again.

"If you're sure…?" He was teasing Cas now.

"I am! I am!" Cas panted, his back arching, desperate for Dean to touch him.

Dean's fingers slipped down the waist band of Cas' boxers – his cold fingers wrapping around Cas; penis, which was throbbing in anticipation. The touch of Dean's fingers created a new sensation in Castiel – one that he couldn't put a name to, but that he would do anything in the world to keep feeling.

"Dean…" He moaned, as Dean had begun, very slowly, to stroke the length of Cas' penis. "De –aaaah!" Dean had run a finger across the top of his cock and a shiver had shot through Cas so fiercely that every part of him quivered.

"Do you like that?" Dean purred into Cas' ear, and Cas nodded obediently, not wanting it to stop. "Look how hard you are Cas – I that for me?"

"Yes… yes!" Cas responded, weakly at first, but then stronger as Dean started to pick up the pace with his hand. Cas was struggling not to thrust with his hips; his whole body felt like it was being engulfed with warmth, particularly his abdomen.

"Does it feel good – my fingers touching you?" Dean asked, Cas was nodding fiercely.

"It does…" He breathed, "Oh Dean, it does !"

"You feel good Cas…" Dean whispered, then unexpectedly placed his lips on Castiel's neck and sucked. This was too much for Cas – the pooling feeling of warmth exploded inside him, and he came with a loud moan – every part of him engorged with this feeling.

Cas relaxed into Dean's tight chest, his eyes closed and his limbs limp – he panted for a few seconds, trying to catch his breath.

"Dean…" Cas whispered, when he finally managed to control the air entering his lungs. "Oh Dean… I love you." Dean's arms wrapped around Cas' chest – hugging him from behind.

"I guess our bond is more profound now," Dean chuckled, then lowered his voice: "I love you too Cas."

There was a long silence between the two of them, as those words which had been unspoken for so long had finally come to pass.

"Shall we sleep now?" Dean finally broke the silence, his voice low and calm; Cas nodded. With a small amount of rearranging, Cas and Dean lay facing one another – Dean placed his hand on Cas' waist, as though claiming his property.

"I really love you Dean…" Castiel mumbled, as he sunk into sleep, protected by Dean.

A/N: I really loved writing this, so I hope you've enjoyed reading it! I'd love to know what you think! :)