When writing any story, a huge aspect of the plot that must always be done right is characterization.  Without complex characterization, there cannot exist an entertaining story.  No one wants to read about another flat Mary Sue or Gary Sue, even if the plot has great potential.  The Twilight series for example could have had great potential creativity wise if the main characters were more complex.  It had an idea to rewrite the vampire lore we were all used to and try to create a memorable romance that was iconically charming.  Instead, because both Bella and Edward, the main characters of the series, were both flat one dimensional characters, the potential it had died out.  Any idea can be innovative, just as long as the characters are complex and relatable.  The only rule besides the characters is to simply not copy an existing work.

  Most people believe only the main characters are important though.  At first glance, that ideology seems like a fair judgement.  Since the plot revolves around these characters the most, they seemingly should be the only ones to focus on.  The problem with this judgement lies with the secondary characters, who need to be just as complex as the main characters.  Complex main characters help a creative idea get off of the drawing board.  Secondary characters with strong complexity give that extra boost needed during the  characters' journeys, whether it be an internal struggle, helping to build up their backstories, give strong character relationships, or make the story feel more relatable.

  A combination of both complex main characters and complex secondary characters can make your story memorable and even more innovative.  The reason The Walking Dead graphic novels are so successful is because of this aspect.  Rick Grimes may be the strong central focus of the plot, but without his group of complex allies, the story would just be another zombie apocalypse tale with no new direction.  This ideology goes for all other stories, existing and in the works as well.  You need all types of complex characters to craft something eye catching.