I'm not the first to suspect or suggest that Arlecchino could be a Hilichurl... but I thought it would be fun to dig into the possibility anyway... I did not expect to stumble upon a possible identity for the Fourth Ranked Harbinger, nor did I expect the rabbit hole to lead me to... "her".

I guess that's what you get when you mix Hilichurls, Alice in Wonderland, and a fiery orphanage director.

*DISCLAIMER*
This theory contains WILD SPECULATIONS, as well as some STRETCHES, very big MENTAL LEAPS, and FALLIBLE INTERPRETATION. If that bothers you... well, you've been warned. Sometimes I just like to explore outlandish possibilities no matter how unlikely they may seem to be at the time of creation.

Also, sorry for the quality of the 4.1 footage. It was accidentally recorded at 1366x768 instead of 1920x1080. This will be fixed for future videos.

*SPOILER WARNINGS*
Archon Quest Chapter 4, acts 14
Ann of the Narzissenkreuz
Ancient Colors
Neuvillette Story Quest (1)
Aqueous Tidemarks
Unfinished Comedy
Khvarena of Good and Evil
Golden Slumber
Dirge of Bilqis

*TIMESTAMPS*
0:00 Introduction
01:12 Hilichurls
08:31 Narzissenkruez
15:52 The Red Empress
29:19 Credits & Bonus MiniTheory

*INVIDEO LINKS*
Arlecchino Design Analysis https://www.tumblr.com/justhereforthe...
Laughing Man Arlecchino Analysis    • Arlecchino: The Black Swan Theory | G...  
The Truth About the Celestial Nail    • [2.6] The True Purpose of Celestia's ...  
Irminsul's True Purpose    • [3.8] Irminsul's True Purpose  Gensh...  

*MORE INFORMATION*
This section is a combination of citations and terms/topics that came up during the video alongside their wikipedia articles (or similar related sources) which should help get you started when doing your own research.

Noah (Islam) https://en.wikipedia.org/wiki/Noah_in...
Hilichurls https://genshinimpact.fandom.com/wik...
Ukko https://genshinimpact.fandom.com/wik...
Tale of Shiruyeh and Shirin https://genshinimpact.fandom.com/wik...
Majuj (In game) https://genshinimpact.fandom.com/wik...
Wadi AlMajuj https://genshinimpact.fandom.com/wik...
Akademiya Team’s Investigation Logs https://genshinimpact.fandom.com/wik...
Akademiya Team’s Investigation Report https://genshinimpact.fandom.com/wik...
Remus https://genshinimpact.fandom.com/wik...
Lyris https://genshinimpact.fandom.com/wik...
Darkwing goose https://genshinimpact.fandom.com/wik...
Caterpillar https://genshinimpact.fandom.com/wik...
Ancient Natural History Excerpts https://genshinimpact.fandom.com/wik...
Lilith (Kabbalah/Zohar)    • Who is Lilith  Part II  The Kabbala...  
Swan Lake https://en.wikipedia.org/wiki/Swan_Lake
The Raven https://www.poetryfoundation.org/poem...
Empty Eyes (trope) https://tvtropes.org/pmwiki/pmwiki.ph...
Necrosis https://en.wikipedia.org/wiki/Necrosis
Gog Magog https://www.britannica.com/topic/Gog
Gog Magog https://en.wikipedia.org/wiki/Gog_and...
Yajuj Majuj https://www.britannica.com/topic/Yaju...
Carter https://genshinimpact.fandom.com/wik...
Rene https://genshinimpact.fandom.com/wik...
Enigmatic Page 9 https://genshinimpact.fandom.com/wik...)
Arlecchino https://genshinimpact.fandom.com/wik...
Lanoire https://genshinimpact.fandom.com/wik...
Cosette https://en.wikipedia.org/wiki/Cosette
Vesta https://en.wikipedia.org/wiki/Vesta_(...)
Remus and Romulus (mythology) https://en.wikipedia.org/wiki/Romulus...