Where there is light,
A shadow appears.
The cause and effect
When life interferes.
The same rule applies
To goodness and grief;
For in our great sorrow
We learn what joy means.
- Sleeping At Last, "Sorrow”
Dean has known Cas for a very long time now. He knew that his eyes always shown the brightest when he fought, and that he was becoming more empathetic when interviewing witnesses than Sam. He knew that he liked to drink his coffee with enough milk in it to turn the liquid almost the exact same shade of tan like his trench coat, not because he can taste it but simply because he liked the activity of drinking coffee. He knew that, if he could, he’d take in every stray pet he came across and care for it.
Dean knew the exact look on Cas’ face when he was hiding something. He could see it in the way he wouldn’t hold eye contact for as long, in the way his hands fidgeted unnaturally, in the way he gave roundabout answers to questions that should be simple. These mannerisms Dean most commonly observed after Cas visited heaven or associated with other angels.
And the thing was, this was exactly how Cas had been acting ever since he returned from saving Jack, and Dean had noticed ever since the shifty way Cas told him about learning the location of Michael.
He recognized that he should just talk to Cas about this – after all, they really couldn’t afford any surprises, especially with where they’re at with the Michael hunt – but things have just been so good after getting Jack back. The nephilim – their son – hadn’t experienced any ill effects since Lily Sunder’s spell, which – Dean just knew that that would bite them in the ass, but it hadn’t, and he’s ready to send a damn fruit basket to whoever he could thank for this.
So he didn’t mention anything to Cas. (But does that really surprise anyone?) And with everything that’s happening, he didn’t even really get alone with Cas to maybe use his excellent detective skills to figure out what’s going on without even asking direct questions.
That is, until he found himself alone with Cas in the kitchen one night. They’re drinking again, but not quite like they were after Jack died. No, this time it’s just a few casual beers and conversation a little too heartfelt to be considered banter. And that’s when Dean decides – now, now is when he should talk.
“If I ask you something,” Dean said, “do you promise to be honest with me?”
Cas didn’t meet his eyes. The beer bottle in his hands must be very interesting. Still, he answered, “Yes.”
Dean waited a moment before speaking again. Tried to prepare himself for the conversation they’re about to have. “How did you get the information about Michael’s location?”
The angel took a deep breath. Traced the label of the bottle with his fingertips. “Honestly? I’d rather not tell you. You are better off not knowing.”
He let this response bounce around in his head for a moment. “Did you make some kind of deal for that information?”
Cas went very, very still. In a very careful voice he said, “No.” A pause. His head fell a bit low. “Not for the information, anyway.”
And – even though he had guessed this, it still hurt to hear. Nothing good ever came out of deals. “Please, Cas – tell me about your deal.”
Another sigh. He began peeling off the label. Still wouldn’t look Dean in the eye. Finally – “Do you remember when I told you about how I escaped the Empty?”
“Cas, what –”
“Yeah, you annoyed the hell out of some kind of entity.” He didn’t quite know where this was going, but he was certain that he didn’t like it.
“When I went to heaven, I learned that its gates had been broken in to by a force known as the Shadow. This Shadow is the ruler of the Empty, that cosmic entity that I awoke.” He paused to let Dean absorb this information. There was a crease between his eyebrows. “The Shadow broke into heaven to claim Jack. The human part of him went to heaven, but the entity wanted to claim the angel part. Wanted to – to drag him to the Empty. So I made a deal with Shadow. His life, for mine.”
And Dean – god help him, Dean uttered what may have been the first legitimate gasp of surprise in his life. “But -”
“I’d do it again.” For the first time in this conversation Cas met his eyes, a steely gaze that dared Dean to tell him that he shouldn’t have made that deal. “I’d do it a hundred times over, Dean. It was an easy deal to make.”
“Then why – how did you make it out of there?” Now that Castiel was looking at him, Dean could see a hundred emotions in his eyes, though he could only really name a few.
“The entity told me that it wanted me to suffer. Instead it will take me when I’m at my happiest. The information about Michael was given to me by Naomi as a reward for saving heaven from the Shadow’s destruction.”
For a moment Dean was sent back to the very night that Jack was born, when Lucifer stabbed Cas and Dean spent weeks thinking that he was gone for good. But he returned – but now he’s going to die again? No. No, no, no.
“Why didn’t you – Jesus, Cas” – Dean swallowed the rest of his beer in one gulp – “why didn’t you tell me?”
Cas averted his gaze again. He had almost entirely picked off the label. “I didn’t want you to worry, what with everything that’s happening.”
“So what, you were just going to randomly let yourself die because you got too damn happy, and you didn’t think it would be a good idea to tell me?” He wasn’t angry at Cas, he really wasn’t – hell, he’d make the same deal too himself. He’s angry at the Shadow or whatever the hell it really was.
“I’m not – I won’t just randomly die. I – I know the one thing that would make me so happy that the Shadow decides to claim me.” The label was entirely gone now.
And Dean knew Cas. Knew him so well it hurts sometimes, like now. Knew him well enough that he’s pretty sure he can guess the answer when he asked in a small voice, “What’s that, Cas?”
And Cas gave what’s perhaps the saddest little half-smile that Dean’s ever seen, and his eyes were bright with pain when he finally looks at Dean again. “You, Dean.”
Maybe it had been in the back of Dean’s mind to finally talk to Cas about this thing they’ve been dancing around, too. To finally accept that they were a they, the kind of they used in the same sentence as couple or together or, in Sam’s case, finally. But now all he could do was touch the hand that’s now stilled around a label-less bottle and tell him, “We’re going to find a way out of this, Cas. I promise. I’m not going to let you die again.”
And Cas was still smiling that sad little smile when he said, “I don’t think there is a way out of it this time,” before he stood and left. But not before Dean watched a single tear slide down his cheek.