Human. That is what Cas is now. Human was what he first scorned upon, the fragile creatures so weak. And now? He became what he never thought would befall onto him. When he turned up on the doorstep of the Bunker, his clothes torn and ripped, and he looked awful, with dark circles in his eyes, the orbs filled with sadness. Dean thought the blue in his eyes had faded to a dull kind of blue. The first words he speaks come out deep and gravely and raw with emotion.
"Help me, please." he begs. And so Dean does, obliging wordlessly, because he knew how lost Cas was. It was so clear in the way he held himself, like a man without a purpose. He lunges forward out of the safety of the Bunker and wraps Cas in a tight embrace. It's snowing and Dean wonders how he isn't dead yet, after all...It had been what seems like forever since he had heard a sound from the angel -no, fallen angel-. So he hugs him tighter and then takes him into the safety of the Bunker where he strips him down and gives him a warm bath, Cas barely noticing of the gesture. While Cas is in the bath, he shoots off a quick text to his brother who is out on a supply run, letting him know that he is out of his depth and he is worried out of his mind. Nonetheless, he digs out old T-shirts and pants of his for his best friend to wear while he takes the remains of Cas' tattered trench coat and puts it in the washer.
When Cas fell, his nights are plagued by terrors. Terrors that leave his heart pounding so hard in his chest he thinks he might die. Half of him wants to, and the other half marvels at how not-dead he was. It would be so much easier if he was dead. Every night he wakes up with tears pouring down his cheeks. He is scared and tired so his sleep-deprived brain tells him to do what he always does for comfort. Go to Dean. So he pads down the cold hallway until he gets to the hunter's room. He hesitates at the door but flashes of his nightmares drive him forward.
"D-Dean." he whispers. A flood of relief makes him breathe out the breath that he has been holding when Dean just tugs at his arm and moves across so the ex-angel can crawl in beside him. The bed is warm and comforting, and the way that Dean's arm is wrapped around him makes him momentarily forget of his nightmares, letting him finally get a decent night's sleep, in the arms of the one man who could provide him so much and not ask for anything in return.
It isn't until Dean walks into Cas' room with the intent on telling Cas about a hunt he realises how bad the best friend is doing mentally. Eyes shut, Cas holds his angel blade high up on his chest hovering about his heart. Dean's face turns white as he quickly grabs the blade from his hands, the fallen angel's eyes fluttering open, clearly shocked at being found.
"Cas, what are you doing?!" He thunders and immediately fell back when Castiel flinches.
"Cas, please promise me you won't ever do that again." Dean mumbles this time and Cas looks into his green eyes and understands. Losing him would break Dean. Cas couldn't comprehend why Dean would care for such an insignificant fallen angel like him, but he nods and mumbles an apology anyway, shaking those thoughts of death from his head, for Dean. And Dean makes sure to hide the blade from the fallen angel.
"Talk to me Cas." Dean sits on the bed next to him.
"I can't hear them Dean" He mumbles and it takes a minute for Dean to understand that Cas means he cannot hear his family.
"Whenever I try...I just hear static..." He looks down at the floor, as if his shoes were the most interesting thing in the room.
"Cas, it's going to be okay. We're your family now, okay?"
"Thank you Dean."
It's a long time before Cas is left alone in the Bunker. They won't be gone long but still, worry curls around Dean's gut. The hunt was simple, nothing they hadn't handled before. A few bumps and scratches. Nothing that wouldn't heal within a few days or a week, tops. But still much to Dean's protests, Castiel had still tried to heal him. With his middle finger and pointer finger ghosting over the older hunter's features. Nothing. Of course there was nothing. He.Was.Human.
"Cas, it's okay." He tried to sooth him, as the fallen angel drew his knees up close to his chest and sobbed.
"Please let me stay Dean. I'm sorry. I'm so sorry. I can be useful. Please let me stay. I'm sorry." He cried uncontrollably and Dean felt as if he had been punched in the gut. He knew nothing could comfort the ex angel so instead he reverts to the only way of comfort he knew; he hugs his fallen angel tightly.
After the angels fell, he was broken. He slept all the time, he barely ate and Dean was frightened. He was frightened of losing Cas. Frightened that he couldn't protect Cas. Frightened he'd fail him. But his fear wouldn't stop him from trying to glue his shattered angel back together. So he fixed him. Let his sleep in his bed every night. Taught him to use a gun. Took him out hunting, obviously they went on small cases at the start but as Castiel started to learn to protect himself, the cases got bigger. Dean didn't think that he would ever get the image of Cas' face lighting up with pride as he killed his first wendigo. Took him to get the anti-possession tattoo and slowly but surely, Cas, though he was still human, was better. Sometimes he'd wake up panting and trying to hold back sobs as he remembered the night he fell but they went away when Dean's protective arm curled around his waist.
"It's okay babe," he whispered.
And so it was. After all falling wasn't that bad. As long as Dean was with him.