I would write episode 3x03.5. (Pretty obvious why). I want to see Bellamy's struggle with deciding who to trust. I want to see his thought process when he decides to side with Pike. I want more struggle. I want way more than they have given. Bell is not one to betray his friends at the flip of a switch. So I would have loved to see more of him in turmoil.
This episode would not change how 3.04 plays out only the process of getting there. To explain to the viewers how it happened. Rather than just telling us it did.
If you could bring back one deceased character who would it be? How would them being alive effect the plot and the people around them that were effected by their death?