Eu não sei se eles podem ser chamados de "teóricos do cinema". Para mim, essas duas pessoas dominam o ofício (por escrito, pelo menos).
John Truby chama essa pessoa de "contador de histórias". Pode ser um dos personagens ou não. Em "The Anatomy of Story", ele diz:
"The storyteller is one of the most misused of all techniques, because most writers don't know the implications of the storyteller or its true value.
The vast majority of popular stories in movies, novels and plays don't use a recognizable storyteller. They are linear stories told by an omniscient storyteller. Someone is telling the story, but the audience doesn't know who and doesn't care. These stories are almost always fast, with a strong, single desire line and a big plot.
A storyteller is someone who recounts a character's actions, either in the first person -- talking about himself -- or in the third person -- talking about someone else. Using a recognizable storyteller allows you greater complexity and subtlety. Stated simply, a storyteller lets you present the actions of the hero along with commentary on those actions.
(...)
A storyteller also lets the audience hear the voice of the character who is doing the telling. People bandy about the term "voice" all the time, as if it were some golden key to great storytelling. When we talk about letting the audience hear the character's voice, we are really putting the audience in the character's mind, right now as he speaks. It is a mind expressed in the most precise and unique way possible, which is what the character talks about and how he says it. Being in the character's mind implies that this is a real person, with prejudices, blind spots, and lies, even when he isn't aware of them himself. This character may or may not be trying to tell the truth to the audience, but whatever truth comes out will be highly subjective. This is not the word of God or an omniscient narrator."
Robert McKee o chama de "narrador" ou "voice-over". Robert McKee prefere mostrar em vez de contar e cortar o que pode ser cortado, seguindo o princípio "menos é mais".
McKee diz em "História":
"Voice-over narration is yet another way to divulge exposition. Like the Flashback, it's done well or ill. The test of narration is this: Ask yourself, "If I were to strip the voice-over out of my screenplay, would the story still be well told?" If the answer is yes ... keep it in. Generally, the principle "Less is more" applies: the more economical the technique, the more impact it has. Therefore, anything that can be cut should be cut. There are, however, exceptions. If narration can be removed and the story still stands on its feet well told, then you've probably used narration for the only good reason -- as counterpoint.
Counterpoint narration is Woody Allen's great gift. If we were to cut the voice-over from HANNA AND HER SISTERS or HUSBANDS AND WIVES his stories would still be lucid and effective. But why would we? His narration offers wit, ironies, and insights that can't be done any other way. Voice-over to add nonnarrative counterpoint can be delightful.
Você pode encontrá-los aqui: Robert McKee e John Truby a>
Exemplos:
- Cinema Paradiso,
- A redenção de Shawshank,
- Coração das Trevas (com três narradores),
- É uma vida maravilhosa,
- O Grande Gatsby,
- Os suspeitos usuais.
Espero ter entendido bem a sua pergunta.