Complex sentence: The creation of Observers was one of the first ideas the writers of "Fringe" thought of when developing the show in its early stages, when they asked each other, "What if there were these characters where all they did was watch?".
Split into simpler sentences: The creation of "Observers" was one of the first ideas the writers of "Fringe" thought of when developing the show in its early stages. They asked each other, "What if there were these characters where all they did was watch?".