I remember being asked the same the same question two times in my life.
What are the words that you use to define yourself? EX: Mother, Father, Writer, Reader, Explorer.
After making a long list choose three.
For a character, three character traits might define them but you see the same traits repeated over and over. Why don’t we get bored of all the superhero movies, detectives, or vampires? Well, that because even when there’s a surge in one type of character or plot the setting is different. By placing the characters in other places you get the opportunity to show them in more than just those three traits.
You can write a character who enjoys playing violin, and thats telling about a character’s interests. But put that character behind the scenes of an orchestra and then you will really SHOW how much that character enjoys or is obsessed with the culture of violins.
I am not trying to say that setting is more important than character but without it, the character would be hollow. By putting our characters in different situations we are more easily able to flesh them out.
When you think of a character from your favorite novel I doubt you think of them alone. You may envision them in a scene or srounded by other characters or in their story world. By contrast you would probably find it much easier to invision your favorite movie character.
In film the audience gets to see everything. Every piece of the world, ever facial movement, every shadow. I know I’ve worked in film. That’s why I find writing so magical. We have to craft our setting without every detail and allow our reader to fill in the details on their own. Therefore what we choose to describe becomes important. It takes on a life of its own in creating the mood, tone, foreshadowing, red herrings, and the subtext.
The very words we use become important (particularly in first person). We can show the characters beliefs about the world, their mood, their predispositions and can be used to show the characters story arc. Having the MC return home and see the setting in a new way is a trick as old as writing (see the first written story the Epic of Gilgamesh) but it’s not cliche nor will you ever hear about it being overused.
For example, Harry Potter would be so different if it were set in the future. It would make the magic less interesting, less dramatic, and it would change most of the drama. Imagine if they had cell phones, any owl related or information retrieval drama letter getting events would no longer be interesting.
I write all this just to remind you not to forget about your story world, even if it’s modern day. Turn your setting into its own character and enchant the reader by letting them see the world through your eyes.