To live in this world, you must be able to do three things: to love what is mortal; to hold it against your bones knowing your own life depends on it; and, when the time comes to let it go, to let it go. ↗
Sometimes a character is really based on research that you do. Other times it's just based on your imagination or perhaps your conversation with the director. Or sometimes all of the above. It depends on the movie and character. ↗