In narrative writing, there are always at least two perspective’s: the writer’s and the reader’s. Works with one first-person narrator may add only this third perspective, but writers can add more perspectives without adding more points of view.
Let’s suppose we’re writing a single first-person scene involving more than one character. The main character will do something (perhaps they will merely think, which is itself an act, but let’s let them do something more dynamic) and tell us about it. This is our perspective on it.
But we don’t receive this information in a context-free way. As a reader, we bring along our own set of feelings and experiences. If the character’s action is wonderful or exciting or repugnant, we feel those things, independently of how the character feels. If the author has written about or implied things beyond the narrator’s words, that’s another perspective (and distinct from the character’s).
And now, on top of these three perspectives, we add the other character. They, too, will have some reaction to the main character’s action. In first-person narration, that reaction will be filtered through the main character’s voice, so we will have to reconstruct it, just as the author had to construct it in the first place.
To convey this multiplicity of perspectives, the goal should not be that all accounts of it are consistent with one another. This doesn’t happen in life, and it’s not very powerful in storytelling. Instead, the goal should be that all accounts of it convey the import of the actions through the lens of each witness, distorted by the lens of each reporter.
Having multiple perspectives doesn’t help us merely to understand what has happened. It helps us to understand the characters better. Sometimes, we can learn more about them from how they react to actions (what emotions did they express? what emotions did they have but deny? etc.) than from what they do.
For me, “what happened?” is often the least interesting question. “How did it reveal our change the characters?” is the question that keeps me reading.