In the film V for Vendetta, the following conversation takes place:
Finch: Rookwood. Why didn't you come forward before? What were you waiting for?
V: For you, Inspector. I needed you.
I have tried to come up with a reason why V needed him, and have concluded that V didn't need him. Rather the author needed him (the police chief) to provide another perspective on the plot: a plot device.
Is that reasonable?