The names for the various Fatui Harbingers stem from an early form of professional theater originating in Italy known as the commedia dell’arte. The commedia dell’arte made use of various stock characters that were given names. These stock characters are where the Fatui Harbingers get their names from. What’s interesting is seeing how these stock characters interact with each other and how they might give us indicators as to the character and story of the Harbingers. I’ll analyze the Harbingers in the known order and save the question mark order Harbingers for the last. The analysis is under the cut and (fair warning) it's pretty long.
Starting with rank 1, we have Pierro, code-name The Jester. His name, Pierro, comes from the French stock character Pierrot, which is actually a rather interesting character for the play. Pierrot is a sad clown who pines for another stock character, Columbina. The Pierrot typically ends up heartbroken since the Columbina character often ends up with the Harlequin (Arlecchino) character. The Pierrot is related to a different, Italian, stock character called the Pedrolino. Pedrolino is not a sad character but rather a character who works to move the plot along. He might do this by helping or hindering the lovers (the Innamorati) who are the main characters of the play. The Pedrolino is also more cunning than the Pierrot and works as a sort of engine for the story. The Pedrolino also frequently has the La Signora character as a lover. Interestingly, both the Pierrot and the Pedrolino stand out from other stock characters as not being masked. Judging from this, Pierro is probably incredibly important to the Harbinger subplot or the Tsaristas' plans.
Rank 2, the infamous Il Dottore, code-named The Doctor. The stock character Il Dottore, is typically an obstacle to the lovers (Innamorati) and thus an antagonist. He is usually self-loving and greedy as well as an older man. Interestingly, the stock character of Il Dottore emerged as a foil to the stock character Pantalone. Il Dottore may be rich, but that typically depends on the needs of the plot. Nonetheless, he is usually an educated individual of some sort, such as a doctor. Il Dottore is meant to playfully parody the educated elite. He is often fond of girls, but dishonest and typically gets caught cheating frequently. In some cases the Il Dottore may be father to one of the lovers, usually the female, or the Columbina in some cases. Based on this I imagine Genshin’s Il Dottore will be connected to Pantalone in some sort of way, though how this may work remains unseen.
Rank 3, Columbina, code-name Damslette. The Columbina is actually a very important female servant stock character. She is sometimes the lover of the Harlequin(Arlecchino) character and wife/unrequited love to the Pierrot character. She might also be hounded by the Pantalone character. She is also more down to earth and sensible than other characters and, unlike other stock characters, may have several masks to confuse the Harlequin. The Columbina character’s main purpose is to aid her lady, the female lover, in gaining the affections of the male lover. It will be interesting to see how this Genshin character works out since her commedia dell’arte counterpart is the one sensible character of the play. She will possibly have a connection to Pierro (as the Pierrot/Pedrolino) and Arlecchino.
Rank 5, Pulcinella, code-name The Rooster. The Pulcinella character’s role changes depending on what part of the social class he is in, but either way he is an opportunistic old man. Though his main motivation is self-preservation he often ends up saving other characters which creates some interest for this character. Judging from Childe’s lines regarding the Genshin Pulcinella he lives up to taking care of others.
Rank 6, Scaramouche, code-name The Balladeer. The Scaramouche (or Scaramucchi) is an interesting stock character. He is always rather villainous and is often beaten by the Harlequin (Arlecchino) character due to his boasting and cowardice. Interestingly, He also sometimes influences the audience to do his bidding. Even though the Scaramouche character’s plotting and affinity for intrigue often gets him into trouble, he usually escapes scot-free and the blame ends up placed on someone else. An in-game example of this could be Scaramouche getting the gnosis from Inazuma and getting away scot-free while La Signora ended up dying. It’s also interesting that Genshin’s Scaramouche reflects the commedia dell'arte stock character’s ability to influence the audience when he tricks the traveler into a dangerous situation by manipulating their rage at their (and Teppei’s) situation. The only curiosity here is if he will lose to Arlecchino in some way.
Rank 8, La Signora, code-name The Fair Lady. The La Signora stock character occupies a very specific role. She may be a courtesan, but is typically the wife of the Pantalone character and lover of the Pedrolino character. She is characterized as tough, calculating, and beautiful though she is frequently overdressed. She often ridicules others which typically leads to her getting in a fight with another female character much like how Genshin’s La Signora ended up fighting Raiden Shogun. The La Signora is more of a sexual character than the Columbina and often has an immediate attraction for the Il Capitano character due to him being a sort of male counterpart of her character.
Rank 9, Pantalone, code-name Regrator. The Pantalone character is actually quite important. He is the money of the play and is typically at the top of the social order. He typically has high regard for intelligence, but becomes the butt of quite a few jokes. That said he can, sometimes, be quite cunning. He is often the father of one of the lovers(Innamorati) and is, for plot reasons, driven to keep the lovers apart. If he is a single widower he hounds most every female character present, if he is married it is probably to the La Signora character. If there is an Il Dottore character present, the two often form a sort of duo. Perhaps as the parents of the lovers or just as the older males of the play. It will be interesting to learn if Genshin’s Pantalone had any relation to their La Signora.
Rank 11, Tartaglia, code-named Childe. The Tartaglia character is often rather dainty and has a stutter. He is a fairly common character and may even make up one part of the lovers. The Tartaglia character often represents the lower social class but sometimes comes from the middle or even upper social class. Genshin’s Childe may be portrayed as more sympathetic than the other Harbingers as a way of mirroring that the Tartaglia character isn’t necessarily bad and may even be one the lead characters as one of the lovers.
Rank ?, Il Capitano, code-named The Captain. Another very common stock character, the Il Capitano is a braggart who claims greatness because no one actually knows who he is, as he is typically a foreigner. The Il Capitano character is typically a coward who will run away from a fight and has trouble talking to and being around other men. The Il Capitano character may be hired by the Pantalone character to guard his daughter (the female part of the lovers). This often results in the Il Capitano character setting up a bidding war for his services between the suitor(s) and the Pantalone character while he goes about wooing the daughter himself. His primary purpose in the plot is to be ‘de-masked’ or stripped of all his confidence and shown in a moment of panic and humility. As such I imagine this character will likely be defeated or brought down in an incredibly brutal manner that may feature quite a bit of humiliation. However, Genshin’s Il Capitano may also be the opposite of what is seen in the commedia dell’arte since Childe’s voice line regarding Il Capitano implies he is very powerful. He may also end up working with (or for) Pantalone which could be interesting.
Rank ?, Sandrone, code-name Marionette. An interesting traditional character. The Sandrone is actually a male peasant who has a wife and child. These characters were originally presented as puppets. The Sandrone character himself is crude, clever, and cunning. He typically makes witty remarks through the play about city life or criticisms regarding officials. Sandrone’s accompanying creature/robot may be a tie-in to the fact that the commedia dell’arte Sandrone was part of a family and was once played by puppets.
Rank ?, Arlecchino, code-name the Knave. The Arlecchino, better known as the Harlequin, is probably the best known of all of these stock characters. The Arlecchino character is a light-hearted, nimbler servant who thwarts the plans of his master and pursues the Columbina. He often competes with the Pierrot character. The Arlecchino character is a sort of trickster and may even be a romantic hero. It will be interesting to see several things about Genshin’s Arlecchino. Will they be connected to Columbina? Will they compete with Pierro? And are they going to thwart their master (Tsaritsa)?
The only primary stock characters not portrayed in the Harbinger group are the Innamorati, or the lovers, who typically fill the lead roles. Everything about the play revolves around the lovers which makes it seem almost like in Genshin Impact the players would fill this role since the plot of the game revolves around the Traveler. The only problem here is that the player can only fill one part of the role leaving the other side empty. Admittedly, since the Tartaglia character does sometimes sub as the male lover it could be argued that only one lover is needed, but this is only if Childe is filling that role and he may not be. Another option is that two NPCs may appear in Snezhnaya and fulfill these roles, or that the Tsaritsa will fill one role and there will be someone else to be her counterpart. However, the Innamorati are often aware of the audience's presence which does complicate matters. This again points toward the Traveler, but does not seal the deal. Either way, it will be interesting to see how the Genshin Impact writers make use of the potential connections between the Harbingers and the commedia dell’arte stock characters.
Edit: The other lover could also be Dainsleif or the Traveler's sibling. Dainsleif is of particular interest since, based on the fact he looks at the camera rather than the Traveler's character model, he seems to be aware of the audience (the players).