WMG / Honkai Impact 3rd

Per wiki policy, Spoilers Off applies here and all spoilers are unmarked. You Have Been Warned.

Rita, "Ningyo", and the scythe zombies are all related in some way

"Ningyo" is a small girl that has Rita's hairstyle and hair color. The scythe zombies are implied to be (dead) Valkyries who succumbed to the Honkai, or (as Chapter 6 shows) failed test subjects; their hair are also similar to Rita's.

The reason Welt is sane even as a Herrscher is because its "Herrscher personality" is in Otto

This requires putting a lot of two and two together, so bear with me:

• Divine Keys are made with Herrscher Cores as component. The 7th Divine Key (Judgment of Shamash), for example, is made from the core of the 7th Herrscher (of Fire).
• Despite the above, the 1st Divine Key, Void Library (held by Otto) and the 1st Herrscher exists together, and the latter explicitly has his core.
• Despite Welt having the Herrscher Core, he isn't shown to have an evil Split Personality even as he uses its powers. This extends to Bronya when she inherits it.
• Meanwhile, Otto is shown to have a different inner personality after he absorbed the Void Library into himself, that urges him to use its power to do whatever he needs.

So it's likely that the "Herrscher personality" of the 1st one lies inside Void Library instead of its core. As for why and how, it's still a big mystery...

• Jossed. The Divine Keys are made with the Previous Era's Herrscher cores from 50 thousand years ago. Welt has a much more recent Current Era core, and the reason it remains under control is also addressed through the story: the souls of 300 000 humans from Berlin were sucked in and form a barrage against the Will of the Honkai that drives the other Herrschers to violence.

Otto and the 1st Herrscher, 2nd take

Alternative theory to the above, assuming that (according to several evidences) different eras have separate Herrscher Cores (e.g both Herrscher Core of Death and the 6th Divine Key existed together, the latter being made from the Previous Era's Herrscher of Death)

While Otto may have a "1st Divine Key", the backstory shows that he acquired it from a strange box. Assuming that it's a similar box to the one that contained the 12th Herrscher (the purplish one), the box might contain the mind of the 1st Herrscher of Previous Era, who's likely the one speaking to Otto from the box. Said "mind" also regularly tempts him to use its power, which might have been slowly corrupting Otto.

Himeko's fate (Spoilers!)

She may actually still be alive in the Imaginary Space (or Sea of Quanta), but having both corrupted by the Honkai and the core of the Herrscher of Flame with her (Vermilion Knight suit), she may end up becoming an actual Herrscher herself^note especially when in the "previous civilization", the Herrscher of Flame was a Himeko lookalike.

She'd be the "awakened" variant of Blood Rose, and would likely be a Quantum-type like Seele.

• Jossed, she is confirmed to be dead in chapter 25.

Otto keeps the original Kiana and turns her into a secret Super-Soldier to be unleashed later on.

• Confirmed, chapter 28 reveals that the original (albeit amnesiac) Kiana has been in active duty the whole time as Durandal.

Theresa really has Kallen's soul (unmarked spoilers)

The "Sanka Saga" event has interesting parallels to the main story, considering it takes place in an Alternate Universe. Chief among them is how Kasumi is actually a clone of Sakura, but with the latter's original soul. Due to her upbringing, however, her character is different from Sakura's. The event's version of Kallen, who didn't realize that Kasumi had Sakura's soul, continued to try to resurrect the dead Sakura in various ways, but all of them ended in failure and she becomes a miserable person.

In the main story, Theresa is a clone of Kallen, but she seemingly has the Kaslanas' drive of protecting the masses. She's ultimately her own person, however. Otto, who wishes for the full resurrection of Kallen, did various extreme and unethical things to that end, and they tend to fail.

This leads to this hypothetical guess that Kallen's soul may have already inhabited Theresa, which is why she's not mindless like the other Kallen clones. And a note to how Otto's endeavor may ultimately be futile.

Rita's extent to Otto's mission

Rita is definitely on board on Otto's plan to awaken the Herrscher of the Void in Kiana's body. Aside from that, however, she's a generally good Valkyrie who fights the Honkai to protect the populace. Otto states (to Fu Hua) that he wants to make a "controllable Herrscher"; presumably, this could give Schicksal an edge against the Honkai, and Rita (as one of the Valkyries that's the closest to Otto) likely knows this as well.

However, Rita may not know why exactly Otto wants a "controllable Herrscher": A Herrscher is proven to be the only one capable of handling the Gem of Serenity, a.k.a the "Core of Death". This gem purportedly has the power to resurrect the dead, which would help in his goal for resurrecting Kallen.

Durandal is the real Kiana

Otto was shown to be able to erase and modify memories with Void Archive's mimicry of Fenghuang Down, he does that to Theresa at the end of the Second Eruption. The Durandal VN shows that her first memories were waking up in a bed to Otto peeling an apple, the exact same scene for Theresa's brainwashing. It is possible that Otto modified the original Kiana's hair colour, erased her memories and gave her a new identity in order to hide her from Siegfried, who knows that he failed to save his real daughter. Bianka's birthdate is listed as January 1st, 2000, meaning she should be two years younger than the original Kiana, however, that is her official birthdate, and Bianka does not know her real birthday.

Bianka Ataegina means "White Reborn" (white referring to Kiana's iconic hair colour as well as the colour of most her battlesuits), and Ataegina is a goddess of the moon, just like Kiana. In addition, Bianka is an anagram of "Kiana B". Bianka is the inheritor of Cecilia's Abyss Flower, and in terms of symbolism, Bianka is Cecilia's heir just like K-423 is Siegfried's heir (wielding twin pistols and a greatsword as of chapter 25). To further reinforce Bianka as Cecilia's heir, their bangs are similar.

Furthermore, Herrscher of Flamescion's theme music in 5.0 trailer as well as Durandal's musical themes for Bright Knight: Excelsis and Dea Anchora in 3.9 and 4.4 trailers share the same motifs and One-Woman Wail.

• Confirmed as the real Kiana in chapter 28.

Kiana has already figured out Durandal's secret.

Upon seeing Durandal's awakened stigma for the first time, Kiana immediately tells her that she finds its power familiar in some special way and asks her what it's about. As Durandal has decided to keep her pre-amnesia identity a secret for the time being, she dodges the inquiry by suggesting that Kiana is probably only drawing a tangential connection to someone else's stigma awakening, as Kiana has witnessed her father's partial transformation as a child. While Kiana doesn't pry any further, from her reaction it doesn't sound like she's fully buying this explanation. As they are preparing to go face Otto a moment later, Kiana explains Durandal her own motivations going into this fight and in turn asks for Durandal's angle on the matter with one peculiarly worded question: "Which identity are you assuming in the fight against Otto?".

So Kiana now probably either suspects they are connected in some way or she'll have already figured out the truth for the most part atleast by the time Bianka finally decides to come clean.

• Jossed, for the most part. Kiana hears the full story at the same time as everyone else in Chapter 34, though similar to Bianka's own reaction, the revelation didn't come as a huge surprise to her.

The 13th Herrscher's title and domain.

Based on the personality and actions of the previous era's 13th Herrscher, she seems to always find positive things to say about the lives of every person around her, tries to encourage others to be open and understanding of those who might seem unpleasant at first and look past their rough exterior, even choosing to willingly sacrifice her own life in attempt to unite her comrades by acting as their common enemy that they could defeat to restore their waning hope and morale for the loosing battle that was the original Honkai War. The official relationship chart published by mihoyo adds to this by showing that she likes literally everyone around her equally.

So, the 13th Herrscher, a.k.a. Elysia, is the Herrscher of Love.

With her characterization and choice of weaponry in mind, her fighting style is also very reminiscent of that of a cupid and thus her powers of rebirth can be said to be in reference to the ever popular ideal that "(True) Love never dies".

To put a bit of poetic spin to it:Love is a part of Life, so even it fades and dies eventually, but it doesn't mean Love or Life itself permanently goes away, as death or tragedy can still fuel the (re)birth of something new.

And in reference to the fact that the 13th is the penultimate Herrscher: Love comes before the End.

• Jossed. Her title in 6.0 roughly translates as "Herrscher of Humanity", but it's definitely not love.

The Elysian Realm will disappear

Having spent so long in the Elysian Realm, Mei is starting to have second thoughts about leaving it behind forever. However, it appears that the choice will be made for her; with Griseo beginning to lift her head and search for answers to questions she hadn't thought to ask before despite herself apparently having a secret that needed to be kept from her, and certain sims either going completely MIA or having their data corrupted, the realm is quickly passing the point of no return. Narratively, this logically ends with the Realm closing forever after telling its final stories, taking all its ghosts with it and leaving the future in the hands of the people of the present. In addition, should the realm shut down for good and the sims go dormant by extension, Kosma will no longer have any reason to keep the truth of Project Ark from Griseo and we may finally learn the truth before the two go to sleep for the final time.

St Freya was a World Serpent base

First off, World Serpent's other name is Jormungandr, which has the same naming convention has St Freya and the various nordic-inspired names used around it (Valkyries, etc.).

Second off, ever since the very first iteration of St Freya's map, a gigantic cobra statue has been a prominent part of the background, and it's still there as of the complete remodeling of the school. Thanks to Mei's efforts in the Elysian Realm, and specifically Mobius's story boss fight, we now know that her Honkai Beast Sesa (it is only visible during a special attack) looked extremely similar to this statue: a giant, very long cobra with odd back spikes.

There has never been any explanation given for the snake being there. Theresa probably hasn't had it installed, it looks old: St Freya's buildings are older than the school since it was only founded in the mid 2000s. It has to have been built by whoever owned the church and surrounding land before.

And what has Gray Serpent been up to for the last five thousand years? Sneaking his snake mama in every religion!

Conclusion: This used to be one of World Serpent's bases of operation. Perhaps there's even some dark secrets remaining in the school...

World Serpent agent Hare is either a clone of Cecilia or the original who somehow survived

The narrative in Ch. 31-EX describes her presence as something that reminds Mei of the time she spent in St. Freya. As we've heard from Theresa and others from various flashbacks, the whole idea of St. Freya as an Extranormal Institute with a more humane take on the Valkyrie lifepath (as opposed to the Military Academy of the main branch) was originally Cecilia's.

In addition, based on audio from Ch. 31-EX (and later confirmed by the developers on the September stream), Hare just so happens to share the same VA as Cecilia in both Chinese and Japanese dubs. While recycling CVs for new characters is standard practice in the industry, especially gacha games in particular, this happening in two separate language releases almost seems like too much of a coincidence.

• Zigzagged as Hare is actually a manifestation of the.Schariac bloodline caused by Cecilia's invocation of her bloods power. To be exact a reincarnation of said manifestation. On a funny note, Kira dislikes her due among other things, her heavily resemblance to Cecilia

House Schariac are related to Elysia

Many of the Schariacs inherent features that are noted to be special about them also have some similiarities to Elysia and the two distinct specialities that are named are their excellent ability to manipulate honkai energy and their "Holy Blood".

Elysian Realm files and Elysia's weapon descriptions draw attention to Elysia's way of controlling her crystal constructs seeming so unusual it’s making it seem like what she's doing isn't even honkai related. However, with the reveal that she's secretly been a herrscher this entire time, it would be logical to assume that all her prior displays of unusual power are still intricately linked to honkai.

The Schariac's "Holy Blood" has been shown to be very effective at negating both mental and physical symptoms of honkai corruption, even to the point of subduing an awakened herrscher personality and reversing the transformation.The result of Elysia's final plan and sacrifice was to somehow give any future generation herrschers her ability to retain their sanity, instead of them going insane as things were before. While we don't know what the exact details or means that were used were, we do know that it did work. At least for some of them.

Schariacs are also shown to be very proficient Abyss Flower users (of its known Current Era wielders, three out of four are Schariacs) that they almost seem tailor made to wield it, since they don't suffer from the usual Cast From Life Force drawbacks under regular use.The Abyss Flower used to originally belong to Elysia before she returned it and it was given to two other users. While her excuse was that it wasn't cute enough (which is still entirely in-character for Elysia) there's never any implication that she had any trouble physically wielding, since the whole reason the topic was even brought up was because Mei and Kevin's sim were discussing the costs one must pay to wield a Divine Key.

Finally, in similar vein to how Kevin's Elysian Realm signet shares some features and its general shape with the Kaslana family crest of his descendants, the Schariac family crest's design bears a vague resemblance to Elysia's signet (notably the three pointed center flower).