Do you think you’d ever be open to introducing Cas and if so do you ship Destiel?
I, personally, am a non-shipper, but I don’t mind anyone who wants to ship the characters in my stories with other characters!
As for Castiel, he actually already is in the stories!
If you check out Brothers Apart, Castiel appears in Brothers Apart 14: Bittersweet Parting. I don’t recommend reading it without catching up with the other stories, as it directly ties into the events that happen throughout the second season.
You can find a full list of the stories here if you needed the link.
Castiel will be seen more in Brothers Apart and a few other BA AUs, but he isn’t a majorly featured character, as these stories are focused more on the Winchesters. His part in the story is very important, but brief.