There is a fan theory circulating that Zandik (Dottore) is related to Rene of Fontaine. Part of this theory is that Dottore is an oceanid that can absorb the memories of other people similar to how primordial water can dissolve and collect the people's consciousness.
As explained in Fontaine quests, when multiple people dissolve their memories and consciousness can be pooled together in a single entity such as an oceanid. Water can take on different forms and manifest in different shapes. So the 'segments' or 'clones' created by Dottore could be based on different people he dissolved and merged with using primordial water. This could also explain Dottore's blue design color and how he wears a vial of liquid by his ear. So would this make Dottore hydro?
So in this way, by being an oceanid, Dottore can live across multiple centuries and be one person while also being multiple individuals.
In this theory, either Dottore is Rene, Rene is a person dissolved/absorbed by Dottore, or Rene is just another scientist who bears striking similarities to Dottore.
Certain fans have pointed out that the research conducted by Rene and Dottore appears inspired by the real-life scientist Rene Descartes, who argued that the human body is like a machine and that the mind and body are separate entities. The mind can function without the body, but the body cannot function without the mind. Rene Descartes is also the namesake for the Cartesian coordinate system in mathematics and is known for his signature phrase: cogito ergo sum (I think therefore I am). Later philosophers such as Rene Guenon built upon this work when writing about metaphysics.
In the Fontaine lore, Rene had a plan of dissolving all the people of Fontaine with primordial water to save them from the cataclysm and create one giant oceanid, one collective consciousness, almost similar to what the Akasha tried to do and the lore of the Golden Slumber. However, Rene did not succeed with the plan.
As is known from Sumeru and the manga, Dottore is known for being a heretic, hence his name Zandik. Dottore was also seen burning the Irminsul and was also interested in research on enhancing humans, creating copies/segments, and Khaenriah machines.
Another part of this theory is that the sanctifying unction used to level up artifacts is similar to distilled primordial water, containing the crystallized memories of people.
A refresher: Rene became an orphan after the Siege of Poisson and joined the Narzissenkreuz Institute. While at the institute, the cataclysm occurred, and the oceanids went to help Egeria in battle. Basil Elton went to fight the dragon Elynas.
After the cataclysm ended, Rene and Jakob traveled to the deserts of Sumeru. On one of these trips, Rene and Jakob realized that their bodies were not like ordinary humans, but were similar to the Gaokerena lotus in the Vourukasha Oasis, the remains of the former hydro archon.
As a child, Rene experimented with abyssal energy and studied Azosite. He found that the abyssal energy had a higher 'priority' over the normal elements as it could possess a will. When Jakob once fell ill, Rene was able to cure him by using abyssal energy, which succeeded due to the unique composition of his and Jakob's bodies.
Rene's research goal was to save Fontaine and humanity from an imminent disaster. Fontaine had experienced multiple floods throughout history. Teyvat also went through multiple apocalyptic cycles. Supposedly the current cycle would be the last one, with no new civilization born after it. This is the prophecy made by Rene's world formula. Other civilizations such as Remuria discovered this as well.
Rene and Jakob then established the Ordo to save the world from the cataclysm. Rene's research concluded that only 'neohumans' could survive such a disaster. He then experimented on Elynas, and Jakob consumed its flesh, eventually gaining the body of a baptist.
Recall that Chlothar found the body of an abyssal creature to be awe-inspiring and perfect. Chlothar Alberich was also leader of the abyss, so perhaps somehow Elynas is tied to the abyss or it might just be the abyssal energy from Jakob. Interestingly, consecrated beasts are also humans who transformed after consuming the flesh of gods.
At this point, Rene thought the neohuman plan would not work and switched to a different plan: to dissolve the people in the primordial waters so they could survive the apocalypse. Rene tested this on himself first and declared that he would save Fontaine and be reborn through water And this is what his name 'Rene de Petrichor' sort of means: 'reborn through rain'. (There is an opportunity for a Cyno pun here.)
Rene was supposedly able to revive Carter and absorb his memories into an Oceanid. His plan then became to dissolve all of Fontaine into a single giga Oceanid to save them from the apocalypse. However, this plan never succeeded, and Rene supposedly passed away in Elynas. That is, unless Rene reincarnated / was reborn as Dottore or was absorbed by Dottore... so the theory goes.
In the Sumeru archon quest (AQ), Dottore also told Nahida that the skies are a lie. Interestingly, Rene's world formula prophecy shows a sky shattered like glass. It is currently unknown if Dottore's remark is related at all to Rene's prophecy, if the two are even linked in the first place.
Actually, as far back as the Unreconciled Stars even in version 1, Scaramouche mentioned that: "The stars, the sky... It's all a gigantic hoax. A lie."
Some of Rene's lore is connected to Evangelion, Scaramouche, and Dottore.
As some fans have pointed out, Scaramouche's story bears striking similarities with that of Shinji in Neon Genesis Evangelion. Gendou treats Shinji a bit like how Dottore treats Scaramouche. Moreover, Scaramouche controls a robot powered by the soul of his 'mother' (Raiden). Gendou's goal was to melt the human race into a liquid (LCL), which is similar to Rene's goal. Evangelion is also known for Qabalah symbolism, which coincidentally also appears in Rene's world formula diagram.
In the Evangelion series, Earth is seeded with two types of space creatures: humans and angels. The humans build robots to prevent the angels from destroying civilization. There had been a 1st and 2nd 'imapct' or cataclysm arising from such destruction. The goal is to prevent a 3rd impact. So this is reminiscent of Honkai Impact 3rd.
Building on the above, some have speculated that the oratrice is a robotic liquid consciousness similar to an oceanid or Dottore. Some fans have even speculated that Dottore built the Oratrice. (However, Rena states that the Archon created the Oratrice.) After all, liquid consciousness could be implanted in meks to power them.
The only comments to be made is that much of this is still theory and not yet proven or disproven by the lore. We just have to wait and see as the story writers can always throw a curve ball. For example, there is another fan theory circulating that Elynas is similar to Durin and may be created by Gold.
At this point, what can be said is that there is strong or explicit evidence that things like Rene Descartes and Guenon's philosophies, Evangelion, Qabalah, Gnosticism, the inverted world tree, hermetic alchemy, free masonry, atomic dust, and cosmic cycles have inspired the lore in Genshin. But as for the specific details on Zandik's relationship with Rene, Zandik's connection to the Oratrice, the jury is still out, and this site withholds judgment until further developments.
Genshin is already a fictional universe. So when theories are created on the lore, it is like creating fictions on top of fictions. When it comes to discussing the lore, we usually try to stick close to existing concrete textual evidence. We only mention this Rene-Dottore-Oceanid theory because certain aspects of it do have a basis in textual evidence, regardless of the veracity of the theory as a whole. As Rena says in the Fontaine AQ: "Whether something is true or not [may not be] that important. The main thing is whether the story [...] is splendid enough."
Literature and literary references are certainly one common way of analyzing the lore and world of Genshin. History is another.
As fans have pointed out, Scaramouche's story does seem quite inspired by Evangelion's Shinji. That is one angle to analyze Scaramouche's character design. And this is a very safe way to analyze Scaramouche, something that is supported by literary references.
History can provide a different angle to view Scaramouche's design and powers. As discussed, Scaramouche's overall design does seem to make a reference to Liu Che, the Han dynasty emperor. During Liu Che's reign, the Han dynasty expanded west and began interacting with many kingdoms in Central Asia, contacting Persian, Sogdian, Indian cultures on the Silk Road. So Scaramouche's presence in Sumeru almost reflects the Han dynasty presence in the western regions during Liu Che's reign. Liu Che was also known for defeating the Huns in the Eurasian steppe, which has symbolic connections to the 'nomadic' anemo element.
The difference between the literature and historical analysis is that the historical interpretation may not be as explicitly stated. It is only something hinted at and may take a bit more comprehensive interpretation of the symbolism and history of the different Genshin regions and characters.
Scaramouche is 6th of the harbingers, while Dottore is 2nd. If Scaramouche is symbolically connected to Liu Che, then what in history can possibly be more powerful than Liu Che, the hero of the Han dynasty? The Han dynasty is certainly a powerhouse in world history, in territorial extent, cultural influence, scientific achievements, etc. being foundational to the modern Han Chinese language and identity. To find things much more powerful than that, one has to start looking into the realm of 'giga-empires', things like the Mongol empire and British empire that have conquered entire continents.
Forget Rene Descartes for now. If Dottore were only based on Descartes, then it would be hard to justify ranking him above someone like Liu Che. As discussed, it seems more plausible that Dottore's power level is more akin to Tolui, the son of Genghis Khan. Also, as he is called the Doctor (博士), it may help to recall that Genghis and the Mongol emperors hailed from the House of Borjigin (孛儿只斤).
And just to put this on record, the 3rd harbinger Columbina's power level may be likened to Columbus, the one who 'discovered' the Americas. We also know what happened to the Native Americans after Columbus arrived on the continent.
Some fans have likened the Raiden Shogun to the 'wife' or 'sister' of Genghis Khan (although there are other interpretations on what Raiden can refer to in history).
Obviously, not every Genshin character has to be based on history. But the thing is, many Genshin characters are actually based on historical characters. Sometimes it is tacit as with Scaramouche, but other times it is more direct. An obvious example: Alhaitham is directly based on a genius Muslim scholar. Given how Genshin nations are based on real world cultures, it would be almost silly to completely ignore the influence of history on character design.
And as far as giga-empires go, the British and Mongol empires are usually considered the top two empires in world history in terms of territory conquered. In fact, many western scholars seem to argue that the British empire was larger.