I read a story sometime last year - Dean & Castiel were the main characters and I'm pretty sure it was slash. It was an AU, kind of post-apocalyptic. I think Castiel was (and had always been) a human. He had some mental issues, and he and Dean lived together. For at least part of the story Dean was in a wheelchair, but had surgery and was fixed by the end. I think he had been a soldier? I remember he had to play a kind of lottery to qualify for the surgery. Also there was some question of Castiel being taken away because of his mental illness, but Dean was protecting him.

Sorry, that's kind of vague. I might be confusing two stories, actually. Hope someone can help!

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