temporarily adopting a lifestyle
For purposes of story, Playing a Role is meant to describe the condition of existing in a certain manner. This does not mean that whomever or whatever is being a particular way is truly of that nature to the core. In fact, it may be put on, as an act or to deceive. However, as long as there is nothing more or less to the functioning of person or thing, it can be said to "be" what it appears to be. Stories often focus on someone who wants to "Play a Role" without actually "becoming" it. The important difference is that to "Play a Role" requires that all the elements of what one wants to be are present in oneself. To "change one's nature" requires that there are no elements in oneself that are not in that which one wants to become.
syn. pretending, appearing, acting like, seeming as, fulfilling a role