"Dean and Sam are coming to visit me today. I've made sure to have my coat washed, Jimmy and I have practiced the joke I will be performing when they arrive".
Cassy they don't care; the Winchesters will just show up and leave. They don't want you Cas, you hurt Dean's baby brother, why would they want you back. They can't forgive you.
"—I'll just sit here and wait for them to arrive".
"Cas don't believe him, they forgave you when you cured Sam. They love you, you're their family. When we find away to get us better, we'll be out of here with them".
Oh Jimmy, always the optimistic one, don't listen to him Castiel. He's human, humans lie.