With two main characters, you may be struggling to determine which of them is your protagonist. Now, even if you choose to write your story from the point of view of both characters, one of them will still stand out as the protagonist — the one the story centres around.
So ask yourself, which of my characters has the most to learn? Which character has the potential for the most growth?
That character is your protagonist.
Now it’s time to put your protagonist in the hot seat. You’ll need to put on your analytical hat, sit in the psychologist’s chair and sift through the character’s mind to learn the essence of who they are as a person.
Why? Because understanding the inner workings of your protagonist’s mind will allow you to write them consistently and believably. In other words, you’ll know how they’ll react and behave in any given situation.