SPOILERS ALERT
For Mort, i lean towards F because whereas Shooter is the part of him which has a 'rational' course of action, Mort hides in his dreamland, and when he goes a little mental, he hides behind his characters, when i'm depressed i lay about and hide in fantasy too.
INFPs can definitely wallow, and become maudlin, rendering them unable to work, Shooter is far less concerned with how Mort feels and takes a far more business like approach ie 'You stole my story,' and you'd better fix it or else.
Since they are both Mort really, they would make a pretty well rounded introvert if used correctly.