Iterator

Iterators are semi-biological Artificial Intelligences used by the Ancients to solve the Great Problem. So far, only two iterators are accessible in-game: Looks to the Moon, and Five Pebbles. However, many other Iterators are mentioned in-game, majorly through pearls.

Description
Iterators take the form of massive superstructures known as "cans", suspended by a number of supports and encased by a thick layer of metal with antennae sticking out of its sides. On the underside of the superstructures, strange green electric storms rage furiously, while on the upper surfaces, a vast city spans the can's length.

Within these superstructures, vast facilities with zero-gravity under the control of the Iterator span the entire area with a multitude of applications, mostly for storing neuron flies. At the heart of the superstructure lies the Iterator itself, often concentrating deeply.

Looks to the Moon / "Big Sister Moon"
Being the senior Iterator of the Local Group, Moon once often acted as the decision maker for her neighboring Iterators. Her interactions with Slugcat show her to be kind and considerate, and yet rather assertive as well. Her can collapsed due to Five Pebbles, her closest neighboring Iterator, leeching off her water supply. This caused her superstructure to lose structural integrity and fail, leaving her in a constant near-death state.

Moon is located in the far right of Shoreline, in the ruined Looks to the Moon facility. If Five Pebbles has granted Slugcat the mark of communication, she will greet it. Her dialogue changes depending on the difficulty being played on. If brought pearls of any kind, she will attempt to read them—revealing much of the hidden lore behind Rain World's walls.



Five Pebbles / "Erratic Pulse"
A calm yet cynical Iterator, Five Pebbles is perhaps the most unpredictable of the entire Local Group. He is responsible for the cataclysmic rainstorms that threaten slugcat.

Pebbles has grown resentful of the "Great Problem" the Iterators are forced to calculate, and hopes to find a fate more suited for his desires. Always holding an interest in the idea of ascension, Pebbles quickly gained great interest in the subject when Sliver of Straw released the Triple Affirmative. Pebbles went undercover in several "Sliverist" groups with the alias "Erratic Pulse". He has held plenty of experiments in attempts to achieve what Straw achieved, but all have ended in failure.

The worst mistake occurred when Pebbles attempted to circumvent the self-destruction taboo by rewriting his own genomes. The result was "The Rot", which continues to plague Pebbles to this day. In his desperation to get rid of it, Pebbles flushed out his superstructure, dumping trash onto the surface—creating the Garbage Wastes. Sadly, his efforts were in vain. Distressed, he began to use even Moon's water reserves in attempts to flush the Rot out, severely damaging her in the process. Due to a senior order from Moon moments before she collapsed, he was forced to stop. He currently desperately attempts to destroy the Rot infection, but has no idea how to do so.

No Significant Harassment
Only ever known as the jokester of the Local Group, NSH doesn't have much said about them. They are either cynical to the point of apathy or simply happy to be humorous. They don't take the "Great Problem", or any problem for that matter, very seriously. However, if the Hunter slugcat is able to reach Looks to the Moon with both the green neuron and its starting pearl, it will be revealed that NSH was responsible for reviving Moon by sending the Hunter to her aid. The exceedingly rare green Overseer is believed to belong to NSH.

Grey Wind / "Chasing Wind"
An Iterator in the Local Group. Though often going unmentioned in the pearls, Wind seems to be a participator in "Sliverist" groups. They grew suspicious of an "Erratic Pulse" speaking of personal Ascension in a conversation, and mentioned it to several members of the Local Group. Wind appears to be an honest and caring Iterator, even going as far as contacting Seven Red Suns in an attempt to help Five Pebbles.

Seven Red Suns
An Iterator in the Local Group. They're a close friend to Five Pebbles, caring about him deeply - Especially when he develops the Rot. Similar to Pebbles, Suns is rather cynical in their views, even going as far to pronounce the futility of the Iterators and their attempts to solve the "Great Problem".

Unparalleled Innocence
Though barely mentioned in pearls, Innocence appears to be Pebble's second closest neighbor. They were responsible for revealing Pebble's condition to the Local Group, though it was all in an attempt to be rude to the Iterator.

Sliver of Straw
A sort of saintly Iterator amongst the rest for somehow achieving self-destruction. She broadcasted the Triple Affirmative to the rest of the Iterators shortly before dying: Affirmative that a solution has been found, affirmative that the solution is portable, and affirmative that a technical implementation is possible and generally applicable. Ever since her passing, Iterators have collaborated and convened in chatrooms in attempts to reproduce her conditions. All attempts so far have failed, however.

History
As their name implies, Iterators were created by the Ancients to iterate—try, try again in solving the Great Problem. They also were tasked with taking control of the Ancients' daily troubles in an effort to help the people achieve Ascension easily. Iterators were created after the Void Fluid revolution, which allowed the Ancients to construct these massive superstructures with ease—hundreds, perhaps even thousands of Iterators were created during this time. Iterators would bring food, water, energy, and other necessities to the cities on their cans. After the last of the Ancients were gone, the Iterators began to work on two different issues—one assigned to them by their creators, and the other brought to attention by the Iterators.

The first issue is the "Great Problem"—the matter of helping "lesser beings", such as lizards or slugcats, ascend. This is a difficult issue—after all, most creatures in the current state of the world are fighting for their survival every cycle, and thus are often completely unenlightened. In addition, the Iterators have no reliable way to speak to or contact these "lesser beings", except in the case of the Overseers. Unfortunately, the relative focus on this issue was nigh completely abandoned once the second issue came into play.

The second issue is the matter of Iterators achieving ascension. Though at first considered completely impossible, Iterators began to speculate and convene with one another on how one could achieve such a feat. Interest peaked when Sliver of Straw, a deceased Iterator, released a "Triple Affirmative"—affirmative that a solution has been found, affirmative that the solution is portable, and affirmative that a technical implementation is possible and generally applicable, according to Moon. Due to Straw's mysterious death shortly after sending the signal, no Iterator knows what her solution was. Many iterators have tried to replicate her solution, but all have failed.

Trivia

 * The Rot seems to be nothing new. Seeing how the other Iterators knew about it when Pebble's case was discovered, it's likely that past Iterators have attempted and failed the same thing as him.
 * NSH is smarter than they look. They discovered that Moon's facility was either failing or collapsed, and sent The Hunter on a courier mission to deliver "Slag Keys". This is the primary goal of the hard difficulty.
 * Five Pebbles seems to grow increasingly frustrated as more creatures show up in their quests for ascension, specifically the slugcats. By the time The Monk arrives, he wishes they'd just leave him alone.
 * At the uppermost region of The Wall, it is possible to make out the housings of many other Iterators in the background. In total, they number at least 10. Adding to this number Five Pebbles and Looks to the Moon, who we can assume is not visible here, 12 total Iterators are featured in-game through more than just text.