Adaptations are in: from comics to classic literature, our films and TV screens are dominated by characters originally convinced for other mediums. The most successful of these focus on well-established characters from stories written decades ago that have been adapted several times before. Characters such as James Bond and Batman are being constantly reimagined and updated. Now these larger than life cultural icons dominate pop culture.

These cultural icons favoured by high-budget film and TV adaptations are the ones we have all grown up with and seen in many different forms. They include American characters, such as Superman from the golden age of comics, and icons of Britishness, such as Sherlock Holmes. Many have changed over and over again to suit each new age, like Dr Who. Batman and Bond have been camp, surreal and moody depending on how we want them to reflect how we see ourselves.

These characters are larger than life. In the recent film Batman vs. Superman: Dawn of Justice, Clark Kent looks up a statue of Superman that is several stories high, an unsubtle way of saying that the idea Superman is bigger than any one person or story. The recent BBC adaptation of Sherlock Holmes featured Sherlock dealing with the consequences of his own fame: the character of Sherlock is surpassed in the public's mind by a mysterious, unknowable figure in a deerstalker hat who appears on the front page of newspapers. In the recent series of Dr Who, the Doctor is not so much a person but an idea woven through time and space itself.

Many fans, writers and viewers grew up with these characters, and as we did so, our understanding of them grew as well. Now that lifelong fans control the companies and broadcasters who own these characters, we have entered an introspective cultural age. Since the 2008 financial crash, western civilisation has been asking questions about what we stand for and what should we stand for? Nowhere is this more apparent than with writers adapting these larger-than-life cultural icons into new stories. Writers are exploring our culture-wide uncertainty about the future by using established cultural icons to ask questions about who we are. This is done by making films or TV series that ask the question who is James Bond or who is Sherlock Holmes?

The larger-than-life status of these characters means that stories which explore who they are often do not fit into works that are believable. Writers have to compress their complex history into a believable human being, and nowhere was this more apparent than in the recent Sherlock Holmes Christmas special that tried to reconcile the present day and the Victorian Sherlock into one story. It ended up being a nonsensical mishmash of two tangentially related plotlines. Sherlock cannot be both his modern self and his Victorian self, and this make sense in a story that takes place in a world which we can recognise as being our own.

The Sherlock Christmas special is not the only example where this approach has led writers astray. Writing a story that asks questions about a cultural icon can led to an excessive focus on character and not enough on story. Most people want Sherlock or the newest DC film to be an entertaining story, not existential musing on the nature of Batman. The story must stand alone and be believable to the audience.

Another example of when the story was not believable was the most recent James Bond film, Spectre. Since Daniel Craig took over as Bond in 2006, we have been treated to a darker and grittier take on the suavely-dressed, wise-cracking spy. These stories have probed the nature of who James Bond is – is he a psychopath, or can he connect with other human beings? How can someone recognise their humanity after killing so many people, and treating almost every woman he meets as subservient to his will?

In the most recent adventure, Bond uncovers an international criminal organisation which has been behind all of the awful things that have befallen him. This global criminal syndicate seems to exist only to test James Bond; it is as if he is the most important person in the world. This has come about through trying to reconcile the icon of James Bond, the criminal enterprise Spector from the classic James Bond adventures, and a story which focuses on Bond's humanity. In our introspective age, James Bond cannot fight a global criminal network as he did in the 1960s: instead, the global criminal network must ask questions about who is James Bond. The problem is, in our world international criminal organisations do not focus their activity on antagonising one person. This makes the story inherently unbelievable.

Man of Steel chose to focus on how alien Superman is, rather than how human Clark Kent is. By constantly putting across how unlike us Superman is, we can see the character as the great culture icon which he is. Superman clearly cannot be human, as no one person can wear so many faces and do so much over the years. This makes Superman difficult to relate to. Audiences are not interested in a protagonist they cannot understand and no one can understand what it is like to be a cultural icon like Superman. This makes Man of Steel quite a cold film, with a protagonist that viewers cannot relate to.

Sherlock focuses on the relationship between Holmes and Dr Watson as the source of most of its drama. This misses the whole point of Sherlock Holmes, solving mysteries. The character of Sherlock has always been seen through the eyes of Watson, as it is the only way he can be knowable to ordinary human beings. However, when writers focus on the internal conflict of who is Sherlock Holmes, or the interpersonal conflict between Holmes and Watson, they miss the extra-personal conflict of the mystery to be solved. Focusing on the character of Sherlock is fine, as long as a good story can be told as well.

In recent years, Dr Who has become very introspective around the nature of the Doctor; an entire plot arc focused on the need to prevent the Doctor from answering the question of what his name is. This focus on the Doctor as an icon has meant that within the world of Dr Who, the Doctor has grown as a character from someone who joyrides through time and space, to a titanic figure who has seemingly touched the life of everyone in that universe. So much has the Doctor grown in infamy, that several times he defeats the antagonist of an adventure simply by shouting "I am the Doctor" at the problem – The Forest of the Dead is a notable example of this.

I can see how knowledge of the Doctor would grow over time in the universe of Doctor Who, but the current obsession with the nature of the Doctor as an icon within his universe has meant that he has grown to become not only godlike but the greatest and only God of this universe. This prevents the Doctor being relatable as a character, makes the dramatic events less believable and the narrative suffers. Any writer dealing with one of these cultural icons needs to avoid these three mistakes.

This age of introspection has produced some good films and TV shows. Batman Begins is a strong example of how to take an established character, ask questions about them and tell a good story. The film was successful in explaining why a man who wanted to fight crime dressed up as a bat and wore a cape despite the obviously impracticalities. It made Batman believable. Focusing on the psychological effect that the death of his parents had on Bruce Wayne made him relatable. Also, turning Batman's trainer into a villain made for an interesting narrative.

There are other examples. Casino Royale is the best of the Bond films starring Daniel Craig. It shows the origin of Bond's bloodlust through the trauma from the death of his lover, Vesper. This is believable and relatable. The film also has a great story. In Sherlock, the adaptation of the Hound of the Baskervilles was their best episode as it had a solid mystery at its core, thus delivering a good story.

From this I can determine that the three important characteristics to bear in mind when writing a story with a well-established cultural icon is believability, relatability and narrative. Writers working with these larger-than-life characters should keep this in mind so that the stories they create are engaging for an audience who are not as interested in asking questions about who is Batman or Bond. Generally, audiences prefer well-written stories focusing on their favourite characters – after all, the quality of their stories was why we fell in love with these characters in the first place.