{Cas's POV}
When I woke up, it was dark in Dean's room. I twisted in his arms, careful not to disturb his sleep, and looked at the alarm clock on the nightstand. 2:19.
I sighed and tried to fall asleep, to no avail. When I was an angel I didn't need to sleep. But even as my grace waned and I did need a little rest, I could fall asleep within seconds. Now, I was not that fortunate. I had heard of humans counting sheep before bed, but Dean did not have any sheep to count.
So, I thought. When I was unconsious, I could hear Dean's prayers.
Cas, listen. I'll fix this. Right now, no angels are listening to my prayers, but I'll figure something out. It's only been a few hours, and I miss the sound of your voice. The last thing you said to me was my name. I promise, those won't be your last words.
Angel, I'm trying. I really am. Sam is searching the library right now. We can figure this out. None of your siblings are answering. They probably are sending all of my calls straight to voicemail. I'm sorry, that was aweful. But I won't give up. Never.
So, it's been three days. I don't know what to do. Sam and I spent all day yesterday reading every book that mentions angels. Nothing, Cas. I feel like I'm failing. I feel like I'm failing you. I don't want to do that. I'll keep going. For you, Angel.
Cas, we ran out of books in the bunker. Sammy's looking through some of Bobby's old books now. I should be helping him. I was, but I needed a break. I needed to see you. So far, we can't find anything. There's not much in the lore about angels in the first place. I should go. I love you.
Baby, we don't know what to do. I don't know what to do. Every turn is a dead end and every lead turns cold. No matter what it is or where it came from, it's wrong or it isn't helpful. I wish you could help. I wish I could just kiss you awake like in some fairytale. But I can't.
Cas, I'm growing desperate. I'm thinking of going into the Men of Letters' experimentation files. I'm worried about what I'll find but I'm more worried about what I won't find. Nothing seems to have been recorded that even comes close to this. Angel, I'm scared. I don't want to lose you.
A week. It's been a week since all of this happened. I feel like I've lost you. I can't though. I haven't, right? You're still there. You're just right out of my grasp. But there. I love you. Please, please, please stay with me. I can't go on without you. Cas, baby, please come back. I know you can hear me, you can always hear me. So, listen. Listen to me, just this once, and wake up. Please.
Cas, I've made up my mind. I'm going to find the experiments. I have a theory. I hope I'm wrong, but then I'll know what to do. Maybe. But I don't know what I'll find. Hopefully nothing. I sincerely wish the Men of Letters didn't experiment on angels. But they might have. I'll tell you if I find anything.
Cas, I'm so sorry. I'm trying. I won't give up, but it may take some time. Hang in there, angel.
That was the last thing I got before my grace ran out. Up until then, my grace was fighting to keep me alive, to keep me as an angel. It would have worked if I didn't go to the bunker. But I tried not to think about that.
"Cas?" Dean yawned. "Are you awake?"
"Yeah. Go back to sleep."
"Dreams?" he asked, sitting up. I shook my head. "Come here." He extended his arm and laid down, pulling me with him. Careful not to touch my scars, he covered me with the blanket. I rested my head on his chest and he ran his fingers through my hair. I've always loved it when he did that. And I drifted off like that. I didn't wake until morning.