So what's a “Core Fantasy”? The definition I tend to fall back on is this:
The Core Fantasy of an Intellectual Property is an assumption contained within the IP about the human condition that affirms something we already believe.
Again, it's easy to give examples, but it's hard to nail down a good universal definition. I say “affirms something we already believe”, which doesn't mean that all Core Fantasies make statements about the human condition that everyone agrees with. It means that we love stories that confirm things we already believe/want to believe. So, if the above definition didn't do it for you, let's talk about what the core fantasy is not.
The Core Fantasy of an IP is not the moral of the story. I would be hard pressed to say that Grand Theft Auto has a moral, but it still has a Core Fantasy.
The Core Fantasy of an IP does not have to be a positive message. Carol gave the excellent example of “Chinatown”, which says that there is evil in the world, and sometimes evil wins, and all you can do is pick yourself up and move on. You could argue that “pick yourself up and move on” is a positive message, but certainly not like “love conquers all”.
The Core Fantasy of an IP does not have to be unique to the property. “Titanic”, “Moulin Rogue”, and “Sleepless in Seattle” all have exactly the same Core Fantasy: Love can overcome all obstacles (even, in the case of the first two, death)
The Core Fantasy of an IP does not have to be tied to any one storyline. Transformers, Final Fantasy, and Bruce Springsteen all have Core Fantasies, but no single, definite narrative.
So, why does anybody care? First let's look at marketing. Knowing your Core Fantasy helps you know who you're trying to reach with this property. The idea that love conquers all obstacles clearly resonates with 13-18 year old girls (other people too, to be sure, but that made up the majority of the people who were repeat theater viewers of “Titanic”). No matter what the events of the story, a Core Fantasy about “going the distance” is going to appeal to primarily men. I'm no marketing expert, so I can't give you a complex breakdown, but if you're going to try to market any mature story, you need to understand what you're trying to say, and who will want to hear it.
Second, it gives you an understanding of how to craft peripheral events. I've thrown around the idea of “thematic consistency” kind of hoping no one will call me out to define it, but ideally, even the not immediately plot important events in a story will contribute to the Core Fantasy, or at least not counteract it.
Finally, it allows you to craft a climax that delivers powerfully on the emotional promise of the story. I reiterate here that the purpose of the climax is more to provide emotional satisfaction than logical satisfaction. If you understand what your Core Fantasy is, you can easily see whether your climax affirms this or not. If your protagonist triumphs over your villain, but not in a way that relates to your Core Fantasy, the audience feels cheated. If Apollo Creed had a heart attack right before the fight in “Rocky”, it sucks, but if Ferris Bueller only succeeds in the end through a massive feat of willpower and endurance, it's just confusing.
So, what does the Warrior Princess (see here for an explanation of the archetype) have to do with this concept? I submit that the inclusion of this archetype requires that the Core Fantasy be close to a certain archetypal Core Fantasy. The closer the Warrior Princess is to the main character, the closer the Core Fantasy is to this archetypal Core Fantasy.
This Archetypal Core Fantasy is not a clear cut Core Fantasy itself, but it is usually a variation on either the power of nature, or the incredible untapped power of the human being itself. Perhaps that humanity, in its natural state, possesses incredible power. It is invariably a positive (though sometimes bittersweet) message, and usually affirms the fundamental goodness of humanity, but also affirms the ability for them to go wrong when injected with hubris.
I considered working backwards through all seventeen of my examples, but I imagine that would be redundant. That being said, though, for your edification, here's my list of core fantasy examples: (Note, this list is confined to games and movies. Music, books, and anything else that can tell a story can have a core fantasy, but I'm keeping it simple)
Final Fantasy – “Nature is more complicated and more wonderful than humanity knows”
Grand Theft Auto, Ferris Bueller's Day Off, The Usual Suspects – “I don't have to play by the rules”
Titanic, Moulin Rogue, etc. - “Love conquers all”
Phoenix Wright, Lucky Number Slevin, Payback - “Eventually, Justice will be served”
Sideways, American Splendor - “No matter how many times you've failed, you can always try again”
Shining Force - “If I champion a righteous cause, people will follow me.”
Star Wars - “One person, no matter how small, can change the universe”
LA Confidential - “Just because I do things differently from you, doesn't mean I'm not doing the right thing.”
I could go on, but I like that list. Now, I throw the ball in your court. What are your favorite Core Fantasies? Do you disagree with any examples I listed? I'd even encourage you to leave comments with some Intellectual Properties, see if I can pick out the Core Fantasy.