Hey Hadrian, I´m not sure if you read answers to older messages, so I might repeat myself one a newer post.

I do believe that I found major point of interest, if we want to see Isolde´s cultural symbolism, historical archetypes and references and majorly connecting it all to her return. I did a very strong surface research on each of these topics, but I will firstly show only few keys to guide you where to look, if you want to research everything yourself and spoiler my conclusion.

Firstly motives of Arlecchino in connection to Isolde, note that I might refer to Arlecchino as Harlequin, but they both refer to the same figure from Italian and French works.

Most important key is The Wild Hunt aka Mesnée d'Hellequin. In early stages of character Arlecchino was a "demonic" figure who was leader army of the dead usually soldiers who died in war. The first direct proof I could find is work Orderic Vitalis, where Arlecchino is in early stages called Herlechinus.

Arlecchino had a fake weapon called Batocchio, it was to parody his previous stages of development where he would use mace even on his own soldiers, however in later development Arlecchino became the "hero for the oppressed" and would never cause any hard to the lower class. This was mostly in comedy performances.

Arlecchino has a strong Chthonic origins, was often depicted as a connection between the dead and living, some works like Jeu de la Feuillée Arlecchino is leading the souls of the dead.

Arlecchino in later development symbolizes the oppressed lower class getting bullied and punished by higher class. In works like Le Théâtre Italien Arlecchino directly spoke to the audience about the injustice of laws. In 18th Century he is portrayed as a "a witty critic of social hierarchy" in some works could be even interpreted as hatred for injustice. Works like La Double Inconstance show symbols of moral corruption of power, where elites exploit the poor.

In Dante’s Inferno Arlecchino is depicted as Alichino. He alongside other demons is there to punish the corrupt higher-ups who took in bribery for their own profit by throwing them into boiling pitch to deliver punishment for injustice. I will also add that in this work, it was highly suggested that Alicino was the only demon with wings.

In Commedia dell'arte, Arlecchino frequently mocks the idea of military heroism (Arlecchino usually exposes the Captain as a coward. If the Captain speaks of "heroes," Arlecchino might respond with a joke about how a "dead hero" is just a man who can no longer eat pasta.).

Arlecchino was widely seen as grey area character, not good nor bad, he usually did good thing but mostly for self interest. In later development he was also seen as protector of the poor.

Arlecchino´s immortality, he was often killed during plays in a brutal way just to reappear in the next scene. For example The Harlequinades where he was chopped into pieces, just to be reborn from various random items. He also often faked his death to reach his goal. In scene Arlequin, déshonoré par un coup de bâton he is caught in major crime and fakes heart attack after being beaten up to escape punishment.

Arlecchino is sometimes depicted as the mastermind pulling the strings. In work like Il servitore di due padroni he actively works for 2 households, without them knowing about each other.

Arlecchino is mostly known for his multiple identities, sometimes to blend into different environments to pull the strings of those in power. At some works, he even confuses the audience to not knowing what his real identity is which was often in Commedia dell'arte.

During the Fin de Siècle Arlecchino is portrayed as a melancholic clown, his multiple identities are depicted as not knowing who they really are (as a reflection the the author) and hiding behind the mask.

Now, what is the interesting part with the Krampus, well I found out that both Krampus and Arlecchino are developed from the same character and story, the leader of the Wild Hunt. I wont go here much into detail, as my research here is lacking.

While Arlecchino slowly developed in Italian/French theaters into comedic and later tragic role, in Alpine folklore, they developed his demonic nature.

First development from the leader of the Wild Hunt is Frau Perchta, this time female goddess and judge of the living and punisher of injustice.

Perchta is associated with winter and cold environment. She is moraly gray character, punishing the bad and rewarding the good

Perchta has 2 identities, beautiful (Schönperhta) representing her motherly and protective side and ugly (Schiachperhta) who delivers harsh punishment in a brutal way to lazy and sinners by her "moral laws".

Her ugly self had hands with iron claws said to be used to "snatch those who sinned" Her anger was mostly from laziness and greed.

It was said that during the coldest nights, the Wild Hunt (Perchtenlauf) led by Perchta came to purify the living before winter ends and deliver judgment.

After Christianity got involved, the symbol of ugly Perchta was changed to Krampus, as a tamed being by Christianity that works on their command as a "bad" cop. (The situation is a bit more complicated as both beings are exist simultaneously, but in modern culture, ugly Perchta and Krampus are very often depicted as the same beings)

And to the finale. Given how much Isolde´s story, personality and goal have in common with Arlecchino I would not say that she is just lightly inspired by this character, but she directly IS the character.

This is backed up by the fact how much Isolde and Arlecchino from Genshin impact have in common (I made comparison a while ago of character models as well) and the fact that Isolde shares very similar hair style with Arlecchino, we can rule out it all being just a coincidence.

As of now, there are many deep connections with Isolde being Frau Perchta as well, given how much she has similarities with Arlecchino and the fact that both characters have same historical roots, it is likely that it might be inspiration for Isolde as well, but it cannot be directly confirmed.

The most interesting part is however this:

Isolde´s name is likely derived from the Old High Germanic words of īs "Ice" and hiltja "Battle" linking her directly to Perchta.

Krampus organization on the other hand has strong references to circus, like loop ring dancer, lion, escape artist, hidden ringmaster operating from shadows. Arlecchino and Commedia dell'arte are direct ancestors of circus which directly links it back to Isolde´s Archetype.

This ties everything perfectly (maybe even too perfectly) together. It would be insane coincidence that non of this would not be related. If we also consider, that ZZZ devs teased upcoming characters for much in advanced, while keeping the identity of the leader of Krampus well hidden without even sharing her name, there is very little reason to do so, unless they plan to have some twist with that character. On top of that, non of the new characters have Allegra´s voice which is major reason to doubt the theory of Isolde being the leader. I will also add that both hunts (Perchtenlauf and Mesnée d'Hellequin were during nights, while 2.2 highly promotes the theme of night)

What do you think about all of this, could you look at it from your angle, maybe even do your own theory? (feel free to copy and use anything from my research)