Is it permissible to write a fictional story in which there are non-Muslim characters?

I have been contacted to write the script of a play. Is it permissible for me to write a play in which there are many non Muslim characters? There will be no display of shirk or any rituals of other religions. I should also mention that the script I have come up with includes a king who does not rule by the sharia. The king is presented in a negative light but that is not because of not adhering to the sharia but because of his pride and greed. There is no mention or reference to Islam or the shariah law.