A little ramble on some of the things I've noticed about their ways of speaking. This post ended up being predominantly about how they refer to one another. Most of this is speculation mixed in with my own views on them and their relationship, without discarding some other possible alternatives (for instance, although I do view them as two AIs that heavily rely on each other to function properly, I do not cast aside the interpretation that they are the same person).
(note: although I have played SB and Ruin, I did not play HW2 myself. All I know about that game has been through let's plays).
Sun is, obviously, the chattier of the two. Not only are his sentences longer, he speaks more of them in a row than Moon does - in fact, we only see Moon going on and on in Ruin (which we will discuss later).
Both of them use a lot of repetitions when speaking. From their infamous "clean up, clean up" line, to Sun's panicked "you like glitter glue? I have glitter glue!" and "light's on! Light's on! Keep the generators on!", to Moon's "hidey hide, hide away" and "bad children must be punished. Bad children must be found", "knock knock", etc. One of the first things Eclipse says is also a repetition ("warning, warning"). They appear to occasionally rhyme their words too, or at the very least use similar sounds in their sentences. This is a robot that works with young children, so it's not surprising.
On that same vein, their main insult to misbehaving children (and employees... or at least Cassie's dad) is also a repetition: "naughty, naughty" (which turns into "naughty boy" for Gregory), "rulebreaker, rulebreaker", and "bad kid, bad kid". In fact, it appears they repeat words more often when they're mad/stressed (Sun's no no nos, Moon freaking out in Ruin). Taking into account they get mad pretty easily when things don't go their way, it's not surprising we hear it so often, but it's neat.
Although both of them speak in an almost song like manner, with Sun's run on sentences flowing well between one another, Moon is the one where this is more evident due to how much shorter his lines are.
Moon is also the one who speaks in a more childish manner. Not only are his phrases shorter, he doesn't articulate them as much as Sun does, and seems to prefer shorter words and sounds, especially giggles. This makes Sun appear more developed. Key word being appear.
Sun tends to speak as if he's entertaining a crowd, doing his best to keep the attention on himself while trying to keep it fun. This is most evident in his level explanation parts in HW2, but it's also clear in SB. In Ruin, this is absent for... obvious reasons.
Both of them are somehow direct in their way of giving orders/saying what they want to do. When they can't be direct, they find workaround truths in order to conceal what they truly want to say, while keeping the main order clear (such as Sun saying the player will hurt their eyes if they work in the dark and ordering them to keep the lights on, rather than saying Moon will kill them so keep that room bright. Direct, but nicer).
Not at all important to FNAF speech lore but I think it's funny: Sun says the infamous Vanny line during the daycare intro section. "Are you having fun yet? (Are ya, are ya?)". 0.5 seconds after Gregory just stands there, which coincidentally is what Vanny does 0.5 seconds after Gregory gets into a vent (numbers exaggerated). I don't know. I just think it's funny. Replaying the daycare section after hearing Vanny yapping that line non stop gave me flashbacks.
The way they refer to each other and the pronouns they use are an entire thing, so let me separate it in two parts.
So that this post doesn't become scrolling hell on the tags, I'll keep it below the read more line:
Sun
Sun is the one who refers to himself the most. He frequently uses "I" or "me" when talking about himself, and does it way more often than Moon. Examples of this are "I have glitter glue!", "I'm stuck in a nap", "it really speaks to me", "I feel dumber just looking at it" - you get the point by now. The reason I'm going hard on this point is to contrast his way of speaking to Moon's.
When it comes to him referring to Moon, we only ever hear it twice. In HW2 he says "He'll wake up if the lights go out!". In Ruin, he says "Not me, the other me!". Besides those two voice lines, he merely alludes to Moon without ever mentioning him by name or by pronouns (such as when he says he'll turn the lights off himself, implying he'll let Moon deal with you, or when he says you can't work in the dark and instead of saying the real reason as to why, he cuts himself and goes "You'll- hurt your eyes if you work in the dark").
This is interesting for two reasons: one, we only see him directly mention his counterpart when he's in a ruined state (the HW2 voice line comes from the mask off section, when they're broken down. At least I think so); two, he simultaneously views Moon as separate from himself ("he'll wake up") and as a part of himself/another side of himself ("the other me"). You can take that as them really being the same "person", or as a reflection of their complicated body sharing situation. Take it as you will.
As far as referring to himself and Moon at the same time, he only does it in Ruin when he states "We need to be whole".
Moon
The way Moon structures his sentences means that he seldomly actually refers to himself directly. For instance, he doesn't say "I will find you" or "I will punish you", putting himself as the subject of the sentence. Instead, he puts others as the subject, wording it as "Bad children must be found" and "Bad children must be punished". This is consistent across all of his voice lines except one... Well, technically two.
To get it out of the way: there's a deleted voice line where he says "I'm putting you in time out", a line he and Sun share and which worked the same way the clean up one does - them saying the same thing, a push towards them being the same person ordeal.
The only in-game time he refers to himself directly is in Ruin. This line is also the only time he refers to both himself and Sun as a duo. This line is also the longest line of dialogue Moon has.
"(groaning noises) Naughty! Naughty! Make it stop! The light makes us hurt! Grind Grind! Grinding gears inside my head! We can't move. Error! Error!"
This line, much like Sun's, is interesting for various reasons. Even though Sun is no longer with him (being stuck in the VR world and separate from Moon, shown by how Moon can't move because the lights are on but his body can't shift into Sun, so he's completely stuck), he first refers to himself as a "us" - adding Sun into the mix. Then he refers to himself alone, "my head" instead of "ours", before going right back to a plural.
We can assume one of three things here: one, Moon refers to himself as a we more often, adding Sun into the mix, a complete opposite of his counterpart who typically speaks in singulars; or two, Sun is not as absent as he appears and in that moment he is in fact with Moon, just stuck on the passenger sit, hurting alongside him; or three, this is merely an effect of this being in the Ruin DLC where the whole point of the daycare section is to fuse Sun and Moon into the Eclipse, so the writers decided to bring the point home further. If you have more options, feel free to add them.
Side note: This voiceline also shows Moon's speaking patterns pretty well. Putting "the light" as the subject instead of "we/I", the rhyming, the repetition, the clipped sentences compared to Sun's endless ones, the noises, the scratchiness, the vague childlike mannerism... All ending with "we can't move", way more straight to the point, said right before he freezes up, which deviates from the "other subject first then me" rule due to the pain tearing through him at the moment.
Moon does not call Sun "the other me" or anything similar in any of the games. He never refers to Sun as if he too was Sun. However, we can assume his view on their situation probably mirrors Sun's - being in the same body and all -, so take it as you will.
And as for Moon referring to Sun as a separate individual... He does not refer to him as a "he". Instead, he actually mentions his counterpart by name, saying "No more Sun". Meaning he's the only one of the the two that has canonically used his other side's name. I think it's interesting how the least chatty one is the one actually calling the other by name and not the other way around. And yes, you can say it's a way of speaking and he's referring to the concept of the sun rather than saying his name, but taking into consideration Sun never utters the word moon, I'd say it's still quite a big thing.
In my headcanon land, due to the happenings at the Pizzaplex, Sun is probably too embarrassed and mortified to even mention Moon. Moon, on the other hand, has no reason to have such troubles besides hating Sun for (in his perspective) keeping him locked in a prison of light. So for me, it makes sense we never see Sun saying Moon's name, and it makes it more impactful when he actually acknowledges Moon as the other me rather than a he.
Eclipse
I lied there's three parts.
Eclipse has very few voice lines. The only one that matters here is "We need to clean this place up before we can open in the morning." This is pretty straight to the point: Eclipse, unlike Sun and Moon, doesn't use an "I". They immediately speak in the plural. They do not view themselves as just Eclipse, but rather as both Sun and Moon combined, at the same time.
As for the DCA being two AIs or one... in Ruin, Sun thanks Cassie after Eclipse is activated. It's left ambiguous. You can say Sun speaking afterwards proves they're not one and the same, "with the Sun and Moon AIs still running separately somehow", or you can assume Eclipse existing doesn't mean Sun and Moon can't keep doing their thing under safe mode, albeit in a less chaotic manner, allowing Sun's voice to come through but not making him any less Moon - he is Moon, he is Sun, and they are complicated yet very simple.
I believe in whichever version is more convenient at any given time, with a preference for "two codependent AIs" given what the games show us. Although, going by everything I collected here, the only theory I believe to just not be supported by canon at all is the one with Eclipse as a separate thing all together. Eclipse refers to themselves as a "we', not an "I". Eclipse activates when you make Sun and Moon "whole". It canonically makes no sense for Eclipse to be a third thing. (Please remember this is a post about what's in the games, the canon of FNAF. AUs and fandom or whatever, you do you).
That's it. Hope you enjoyed my rambling. Uh artblog unpaid promotion @tagidearte thank you for making it this far.
