Angels didn't dream. Castiel discovered this as he drifted into unconsciousness in the quiet of a motel room. He did not run through a fantasy land or some imagined future of peace. His mind did not even create a relaxing escape as he knew so often filled Dean's few hours of sleep. Instead, he found himself in somewhere familiar. It was a large expanse of open green grass which was situated roughly where modern day East Stockholm now stood, but this was centuries beforehand when humanity was still such a young species.

His vessel was a small but strong twelve year old boy who had been cut off from his family and tribe by a harsh winter. He had barely understood what Castiel asked of him but seeing as his other choices were waiting to either starve or freeze to death he had agreed eagerly.

Cas remembered that winter well. It was his first journey to Earth and his first vessel, so he had been allowed that winter to explore his father's creation. He flitted around the globe watching predators hunt, fish swim and leap, and humans with their early sketches of the civilisation they would build.

All of God's creatures were magnificent and Cas would spend hours with each one, but his favourite by far were the birds. He spent weeks finding each species and watching them fly, standing close when they slept as only an angel could, finding every detail in their feathers.

The first similarity he found was in a large golden bird, an ancestor of the Golden Eagle, where he saw the golden flecks in chestnut feathers almost identical to Gabriel's wings. Then a Raven with wings that first appeared solid black then shone under the light with vibrant greens and purples just like Raphael's. Michael's came to him in the form of a hawk coated in dark red like a sunset in a thunderstorm.

An overwhelming sadness filled him when he finally found the sleek white feathers of Lucifer on a proud looking swan in which Castiel could see the effort which their father had put towards it. It pained him to think of Lucifer's wings, which looked as though they had been woven by the very cloths of heaven, now tattered and stained with his own blood. Cas knew he would not find their like anywhere on this world.

Slowly he found the likeness of each of his kin. A dark grey for Zachariah, the deep green of a tropical bird for Anna, even the fluffy teal of Joshua's prized wings. He was so preoccupied with marvelling at his brothers and sisters made again in their father's new work that it took him by surprise when a little bird, no bigger than the palm of his hand, hopped up to him. It stood on a branch by his right shoulder and cocked its head inquisitively. Its tiny wings were a swirl of blue and black that Cas recognized instantly.

They were his.

Just the thought that his father had one day carved out of the cosmos this little being just for him made Castiel feel more emotion than he had any right to as a warrior of heaven.

Holding out his hand to the bird, it hopped towards him and onto his forefinger. Its little talons gripped securely and it peered up at him, no hint of fear in its eyes despite being so small and he being so big. They stood there like that for a long time, before eventually the tiny creature decided it must move on. Naturally, Castiel followed it.

It flew about darting at the ground picking up grubs and things to eat. But rather than eating them there it would fly up into a tree and disappear before coming back for more. Eventually Cas's curiosity got the better of him and he followed the bird up the tree. Perching on a branch he watched as his little friend darted into a small hollow. Peering inside he found a group of baby birds in a nest of sticks, leaves and feathers. They were chirping loudly but would quieten when his little blue bird gave them a grub of worm to eat.

What confused Cas was that these birds were already larger than the blue one and their grey baby down was already starting to be replaced with deep brown adult feathers.

They're not its young.

This was obvious enough but what he couldn't understand was why? Why would this little bird with all the troubles it must already have to look after itself or trying to have its own young bother with looking after these birds that weren't even the same species? Castiel pondered if he would sacrifice anything for anyone that wasn't his family, but he couldn't think of any situation where that would even be a consideration.

Shaking himself out of the memory and remembering that this was a dream, Cas laughed to himself. If only his younger self knew that God, in all his wisdom, had not just given that bird some blue and black feathers and left it at that. He had known all along that Castiel would fall on the side of the humans.

Maybe this is what he wanted for me then. Maybe I am not a traitor but following the path laid out for me.

But that didn't make any sense. Why would his path be destined to interrupt the path of others? Why would his fate be to stop something that was set in stone by God himself? No. It didn't make any sense and he shouldn't try to justify his treacherous actions because of an observation about a bird.

He skipped ahead the rest of his memories until he stood back in that large expanse of grass that stretched across the ground like an ocean. It was broken up by the occasional tree and the grass itself was long and thick. It was long before the time humans started cutting it.

He was watching a caterpillar crawl up a single blade when he heard the faint sound of wings behind him.

"Cas!" he heard the greeting as he swirled around.

It was Balthazar, whose silver coloured wings Cas had found on a bird over the sea. Apparently the only way their father could achieve the silver shimmer was by having them constantly dripping with water, reflecting sunlight in soft sparkles that Balthazar had naturally all the time. Castiel smiled internally as he realised that before Sam and Dean, Balthazar was the only one who ever called him 'Cas'.

"I'm so glad you made it," he smiled. His vessel was a tall man with wavy blond hair like sunlight rippling down his back.

"I wouldn't be late for this," Castiel smiled back.

This was his first lesson. Balthazar was to teach him how to be a warrior on Earth, in a human body. Cas was just thankful with who was chosen to teach him, and mainly that it wasn't Zachariah. At least he knew that Balthazar would forgive any mistakes, whereas Zachariah was notorious for being ruthless with 'failure' as he called it.

"Let's get started then," Balthazar grinned.

They started with the simple moving position. 'Zapping' was what Dean called it. He had gotten the hang of this during his stay over the winter so they swiftly moved on to zapping to a moving target. There were no cars or trains obviously so Balthazar found a butterfly, released it and told Cas that he had to zap to a position and catch the butterfly without taking a step or zapping again.

It turned out to be harder than Cas thought and it took him six tries to catch the butterfly. When he came back with it held gently but securely in his hand, Balthazar beamed with pride.

"Nice job brother!"

Cas gave a small smile, it made him happy to know that his brother was pleased with his progress.

They spent the next few hours training. Balthazar showed him how to wield an angel blade, how to channel his power through his hands to smite a demon by touch and finally how to focus his grace into a blast.

It felt strange to Castiel, to fight in this body. The new feeling of the human form through him off guard and caused him to be overpowered several times by Balthazar who held the blade to his throat for a split second each time before laughing and teasing him on his clumsiness.

Hearing that laughter again made him strangely sad. Balthazar laughed freely and often, and perhaps was the only angel to do so. Save maybe Gabriel.

They took a break once Castiel had grasped the basics. There was no need, they could have continued for days without growing tired but Balthazar was all about free time so they took a walk.

"You've been awfully compliant Cas," he frowned about half an hour in, "don't you have any questions?"

He pondered the thought for a moment before answering.

"I wouldn't really know where to start, there's so much I do not know yet."

"Well what do you want to know?"

"I guess," Cas paused uncertainly, "I guess I would want to know why our wings are invisible. Why can't they manifest properly on Earth?"

"Ah see I knew you were a curious one," Balthazar smiled with a glint in his eye, "Our wings are part of Heaven; they're what ties us to it. They can't be here just as Heaven can't be here."

"So we can't hurt our wings here?"

Balthazar's expression grew dark at the question and Cas's curiosity peaked.

"On the contrary, our wings are what we must guard the closest."

"But you just said…"

"They are not able to be damaged by anything physical. We don't need to worry about weapons or falling on them or any threat posed by an average battle or fight."

"Then what can they be damaged by?"

"Well they're our connection to Heaven right? So anything that threatens that connection threatens our wings."

"I don't understand," Cas admitted.

"If your allegiances were swayed, if you started fighting for another side… Your wings would suffer, as would the powers gifted by your Grace."

"What would happen to them?" Cas asked, horrified by the thought.

"Your powers would just weaken, but your wings…" Balthazar looked genuinely disturbed, "You have to understand, this isn't a consequence of one broken order or a single feeling of doubt. This can only happens if something makes you deny your allegiance to Heaven. This is one step short of falling."

Castiel was hooked on to Balthazar's every word, and though the subject terrified him he nodded for his brother to continue.

"It starts with an ache, but can quickly lead to spasms and paralysis – your wings go numb," he added seeing Cas's look of confusion at the medical term.

"That sounds awful," Cas said sternly.

"It's reversible. To begin with. The more it happens the more likely it is to become permanent, until eventually the feeling never comes back to them. That's when you know."

"Know what?"

"That you've fallen."

"But how could you have fallen! I thought your Grace had to be ripped out?" Cas was aghast.

"Normally yes, but to deny Heaven so completely severs your connection with it. It's as though your Grace slowly returns to Heaven without you noticing until you can no longer feel it anymore. Remember Cas, you are not an angel without Heaven." Balthazar had stopped walking and was looking Castiel dead in the eye with a serious glare that seemed so foreign on his face.

"Of course, I shall not doubt brother," Cas gifted this rare solemnity with his own.

Balthazar broke into a grin.

"Good!" he swung an arm over Cas's shoulder, "What shall I beat you at – I mean teach you next?"

Cas woke up with a start, his face still buried in the motel pillow.

Oh I was so wrong.