#i remember someone saying it was because Joar/James requested that they changed some parts of the dialogue

[colfy-wolfy]

Not counting downpour dialogue, it isn't directly stated that moon and pebbles specifically are "siblings". They are giant semi-organic robots so what they count as being related is most likely very different from ours and could likely only a social status type thing.

From what we know within vanilla canon is that Pebbles was built closer to Moon than normal. As a result, Moon and Pebbles share groundwater and possibly other resources. Their creators knew the risks when building pebbles so I think it's safe to assume that they did this in a haste. We don't know how exactly the iterators were given their names/statuses. As far as we know, Moon is the only iterator within the local group with an alternate name within chat logs (Not counting Pebble's pseudonym since Erratic Pulse was used purely to conceal his identity)

Moon's log name could either have been given by the local group, assigned to her when she was made group senior, or simply a name she has given herself. If it were given by the group, it could either be because the group sees her as a sister to them all or she is known to be almost like a sister to Pebbles because of their close proximity and shared resources. This could also the case for if she gave herself the name, seeing herself as a big sister to her group or to Pebbles. If it were assigned to her, it could very well just mean "big sister", "big brother", or "big sibling" is a status given to local group seniors. Two or more of these could be true at the same time as well but there isn't really much if any solid proof that I know of that would really say for sure.

also another thing to keep in mind is that I believe Joar and/or James did have some part in downpour's dialogue, changing things to how they see most fit with their personalities and maybe the canon vanilla lore. We can't know for sure until it's directly said, but some dialogue where its directly said that Moon is Pebbles' sister could possibly be canon to vanilla as well or solely only canon to downpour. So the conclusion? Their sibling relationship is largely fanon/headcanon and only vaguely implied if you squint. I wouldn't say "collectively hallucinated" though, seems a bit rude to me, but I digress. I do personally see them as siblings for the fun of the dynamic alone (And I'm sure that's also the case for most people) but if you personally rather stick fully to canon and not see them as such, sure! Also adding onto Void's reblog; If we're talking downpour, then yes, it was also stated outright that Moon is his sister in Rivulet's ending.

Okay so apparently the entire fandom may or may not have collectively hallucinated moon and pebbles being siblings or having an actual sibling-like relationship and referring to/seeing each other as such ??? Because so far I have found nothing in any of the vanilla pearl dialogues or even moon and pebbles' own dialogues (they only refer to each other by name or as "friend") that clearly points towards that The "Big Sis Moon" title is her username in the local group, but not specifically in relation to pebbles- could just be that she sees herself as the "big sibling" / "parent" friend of the group ? And she does say "our parents" but she might be saying the "our" in general (our parents being the parents of all iterators and not just the parents of specifically her and pebbles) ? If anyone can find vanilla lore bits that point at them being stated as siblings do show- because im legit interested in knowing if it's actually there and I missed it or if we really just all sorta assumed this bit of headcanon is fully canon ?