I tried so hard not to get sucked in. You can see how well that worked. These are mostly Castiel and Dean centric. Sorry Sam.

Talking to Air
Tired with lack of angelic assistance when they need it most, the Winchesters convince Castiel to give them a way to contact him. He makes no promises as to answering. A few connected scenes. AU halfway through season 4. PG-13, no pairings COMPLETE.

Star of the Morning
Chapter 1 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Chapter 7 Chapter 8
Castiel, removed from his host, is forced to make a temporarily substitution. Dean is so not onboard with this plan. Post The Rapture, AU. PG-13, no pairings COMPLETE.

Loyalty
Chapter 1 Chapter 2
Post On the Head of a Pin, pre The Rapture. "You never found out who was killing angels. Or how. But now you know." Dean discovers he and Castiel have more common enemies than he thought. AU, PG-13, no pairings COMPLETE.