"Uh, what?" Dean is confused.
"I am aware that Gabriel once informed you of my unusual status," Castiel says, as serious as ever. "How I am the only one born, not created. The result of the grace-bonding of two angels."
It takes the siblings a minute to remember that conversation with the archangel Gabriel, so long ago when apocalypses had been simpler.
The dark-haired angel continues, "Sariel is one of those two angels, my grace began and grew within hers until I separated and became me."
"That's actually kind of interesting," Sam is curious about such an unusual event. "Who was your father?"
Castiel meets the blond angel's eyes, and she looks away. "He was lost in the first civil war," the male angel eventually states.
"I'm sorry about that," Sam says earnestly.
"Could we have some time to ourselves?" asks Castiel, "It has been millennia since I've seen my mother."
"Yeah, I get it," Dean answered, reminded again that his friend isn't human, not truly.
Sam and Dean both leave the infirmary, allowing the two angels their privacy. Castiel sits on the bed across from his mother and both remain silent a long time. Sariel senses that her child is trying to get his thoughts in order before speaking and allows him his time. Eventually Castiel speaks, in enochian to prevent the brothers from eavesdropping.
"I know the truth now," the younger angel sighed. "At least, I know the basics. I met Gabriel, and he told me, he showed me the truth."
Immediately Sariel knows what her son is talking about and she looks down at her lap with a frown.
"I'm sorry." Neither is sure if she's apologizing for him finding out, or for the lies he had been told.
"Why?" asks Castiel.
"Some of it," the older angel sighs heavily, "Some of it is because I wanted you to have a normal life… Well, as normal as possible. And if everyone knew who your father was… There was a good chance you would be, at best, an outcast."
"Gabriel said the story was one that Michael came up with."
"Yes," admits Sariel. "Michael wanted nothing left that was tied to your father, but because of the unusual circumstances of your creation he was unwilling to kill you… Or me. But he felt he had to remove any connection to his brother. So he cleared everyone's mind of it and invented the story you knew."
"That's why we always had a guard, isn't it? So you wouldn't tell me the truth?"
"Yes. If I ever strayed from the story, he had threatened to kill both of us."
Castiel looked up sharply at that, he had never realized how precarious a position they had been in. He's quiet a few minutes, unsure how, or if he even should ask his next question. Castiel starts to speak a few times before finally asking, "Gabriel said you didn't fight, that your… that Michael was responsible…"
Sariel understands what he is asking, and a muscle tightens in her jaw, but she can tell the truth now, and since Gabriel already apparently over-shared there was no point in hiding it. "He did," the female angel admits roughly.
Castiel doesn't know what to say to that. The loss of flight was the worst thing that could happen to an angel, and to have pieces of your wing deliberately cut off? And then only flock, only direct family was supposed to touch another angels' wings.
"If… If you had fought… what side would you have been on?" Castiel has to know.
The blond is silent for several long minutes, trying to find the right words to say. Finally she admits, "I don't know. I truly don't. We tried to prevent it, but things just kept spiraling until no one could control it anymore."
Castiel accepts this answer, it is one he can understand. Torn between duty to family and duty to heaven, between love and responsibility. It is a position he has found himself in too many times in the past few years.
The heavy weight of the past hangs between them and the two angels sit quietly for a while, allowing the weight to dissipate and simply enjoying being together again.
"You have been busy in the past few years. I know only the vaguest details of it, what has happened?" Sariel finally asks.
Switching into English, Castiel replies louder, "Perhaps Dean and Sam would like to help share, they have been a large part of much of it."
Sheepishly the brothers re-enter the room, attempting to pretend that they hadn't been hanging around outside the door hoping to hear something. They sit on the bed next to the two angels and the three males begin sharing everything that had happened.
Castiel begins with an abbreviated history of his time in the garrison. The humans chime in when he reaches the reaches the story of the apocalypse, version one, adding their own bits of information and arguing about the small details in the way siblings do. Castiel does not deflect from the mistakes he had made, such as his releasing the leviathans and the brutality of his own civil war to prevent the apocalypse from re-starting.
They reach the story of the tablets and of how Castiel was tricked into completing the spell to close heaven. When they share the story of Gadreel, how he helped them, was misled into assisting Metatron and how he realized his mistakes, Sariel sits up paying close attention. Castiel shares how they are caught by the conniving Metatron, and how Gadreel almost gave his life getting them out. Castiel shares that Gadreel had barely survived and been brought back to the bunker. After recovering, the elder angel leaves, claiming he needed to figure himself out, and begins to travel the earth.
The relief that Sariel feels is very evident and Sam is the one to ask why she is so relieved.
"Reel is one of my brothers," Sariel shares, "We are close."
Castiel is surprised by this information, he knew the angels were created in groups that became true siblings and that he must have aunts or uncles, but he didn't remember any of them.
They finish their tale by discussing the Mark of Cain that Dean now bears, and their search for a way to remove its influences. Dean's brief stint as a demon is mentioned, much to his chagrin.
They reach the end of their tale after quite a while. With no where else to go, the brothers offer to allow Sariel to stay at the bunker with them and Castiel, an offer the older angel accepts knowing this is a good place to recover.
It is closer to morning now, and the two humans head to their respective rooms to get some rest. Castiel shows his mother around the bunker, or at least the areas that the team has managed to catalogue and deem safe. The two angels spend the rest of the night talking, mostly it is Castiel sharing what he has learned of human culture and how much is still confusing. Now that she no longer had to hide the truth, Sariel also shared many stories from Castiel's childhood, often memories that had been taken from the young angel although some were also of times before the first civil war, when everyone was happy and everything peacefully.
(Yes, Gadreel survived in this. Mostly just because I really like the character and think he deserved better, but there is another plot reason as well lol)
