AN: Still catching up on SPN, so please avoid spoilers for anything after Season 5 Episode 12.
When Castiel senses a presence behind him, he knows who it is. He has been expecting this for three days; ever since they left Wellington. He doesn't turn around.
"Gabriel," he acknowledges. "The Winchesters aren't here."
"Oh, I know." Gabriel strolls into sight, but Castiel still doesn't turn his head. "Can't a brother stop by just to say hello?"
When Sam and Dean talk about being brothers, it runs deeper than obligation. There is more to family than blood, and Gabriel... Gabriel has been gone a long time.
"You never have before."
"Well, I guess it's now or never. It is the end of the world, after all!"
Castiel doesn't reply, and there's a moment's silence before Gabe speaks again.
"I heard you and Zachariah had something of a... disagreement."
"I fell." He isn't afraid of the word; he always knew the consequences of rebellion.
"You must get lonely." Gabe smiles. "It sure seems quiet down here sometimes."
"You could always go back."
He doesn't mean to say it so transparently, but it's true. They are not the same. Gabriel never did more than stumble.
The smile disappears.
"You think this is easy? Because there's a reason fences aren't something you sit on, Castiel, and it's not because they're comfortable."
"I think that some of us never had that option."
He tries not to resent the unfairness of it all: that Gabe was simply allowed to leave. Michael never ordered him back, so he never disobeyed. He never had to deal with Zachariah, forcing him to pick one thing or the other, taking away the luxury of indecision.
"So you think I should choose. One of my brothers over the other."
The venom in Gabe's voice is real, and Cas wonders what it was like. He never really knew Lucifer; perhaps if he had, he could understand. Perhaps not. He isn't sure what's worse: that none of his brothers seem to understand what family is supposed to be, or that, maybe, a few of them do.
"You know, there are more than two sides to choose from." He forces the words out, but he has to offer.
Of course, Gabriel laughs.
"You mean join your little gang? Team up with the chuckleheads? This is the big leagues, Cassie! It's the Superbowl, and you're betting on an anthill?"
Castiel can't help but turn, and for a moment, their eyes catch.
"You've been on this planet longer than I have. Haven't you ever found something worth believing in?"
There is no reply; Gabriel is gone.
Castiel hopes he found what he came looking for. Either way, he has nothing else to give.