Two Fallen Angels ( SPN fanfic)

Castiel and Cassandra fall to Earth. They cant get back to heaven. But Castiel does know on who to get help, Sam and Dean Winchester. Castiel was the one who took out Dean from hell. Ever since then, their roads have been rough but they still go through. Cassandra, its her first time since the ice age being on Earth. Will they be ever to go back to heaven? Or will they stay? Choices are hard for the Angels fallen from heaven. (A SUPERNATURAL FANFIC YEAAAAAAA)