1. It's an FBI Agent AU where Dean and Cas are both with the FBI. They already live together, sharing Cas's apartment, and then decide to get married because the benefits are cheaper. Dean was a veteran and PTSD from his service. There was a part where he took the shrapnel and used it to make Cas's ring and it was really emotional and stuff.
Sam and Ruby were together in this fic, too. I think Ruby had cheated on Sam and gotten pregnant but didn't know who was the father of her baby.

This was posted to AO3 but I can't remember the title or the author to find it again.

2. Cas was Dean's handler in the FBI. He was a part of the KGB or something and had his throat slit so he couldn't speak but they communicated via sign language. There was a warehouse or something that Dean went into that was under surveillance but was rigged to explode so he charged in to get some people out. Before he went in, he signed to the camera 'I love you' for Castiel. He lived, though, and then they went home and had happy-fun-times in the shower. I'm pretty sure this was posted on AO3 as well.

3. Dean was a nurse, I think, and Cas was a doctor. They were best friends for a long time and Dean had always been in love with him. Cas was married to Amelia/Daphne/somebody and she didn't like Dean because she knew he was in love with her husband. Somehow, Amelia/Daphne/whoever dies and Dean helps Cas through that and I think they're at some hospital function or swanky party where they finally reveal their feelings for one another. That's all I remember for this one and I've been trying to find it for forever!