Fonts need to be relavent to the film's story and general emotion they portray to the audience.
The font used in a film can show the audience what type of category (genre) the film would fall into. It is a brief telling of what the nature of the film is and what perhaps it may contain. For example, a horror film may have white titles which fade into the screen and fade out gradually. As this contains a ghostly theme the film opens with, this may indicate to the audience the nature of the film and what type of film it is. Fonts in a title sequence can expose hints about the story that we now won’t need to be told (like the example above, indicating there may be ghosts).
The font in the opening of a film has to be relevant to the theme it is aiming for; this includes the size, shape, colour, animating effect and movement of the font. They have to be associated with the genre/storyboard of the film to give the audience an idea about the films content.