Originally Posted by JimHull
LOL, nice one dmizzo - The problems in "Casablanca" exist because there are two letters of transit that have gone missing. Letters of transit that Lazlo was going to use to get to America. Everyone wants those letters, but it is Lazlo who is driving the pursuit towards them (both because he is in Casablanca and because he wants them for his own self-interest). Strasser is actively trying to prevent that from happening (Antagonist). Once Lazlo gets those letters, the problems in the story are resolved and the film is over.
The Main Character - the one we experience the story through is Rick. Through him we get to feel what it is like to be someone who goes from an attitude of not sticking their neck out for anyone, to someone willing to take action for the benefit of others.
I could well be getting this all wrong, but the main message I'm seeing here is that you believe that whoever wants something the most is the Protagonist.
In The Terminator, that would make The Terminator the Protagonist because what it really really wants is to kill Sarah Connor. In fact, it's the sole purpose of it's existence. And this would make Reese the Antagonist, because he is standing in the way of that goal.
I know this is surely something of an oversimplification of what you're trying to teach, but I think I can see why the OP was getting a bit muddled up.