OnS Theories (S5) - Fifth Theory - Mahiru and Guren. A promise that will last in eternity, and the sacrifice required to save humanity. Warning: Long theory
This will be one of the longest theories I'll share or update. I've been quite dull or not motivated when it comes to theories (honestly I should be motivated, the story is going to reach a new phase but well, let's proceed!)
The last 3 chapters of the manga made us understand that Guren plans to do something in the dark in order to achieve this "betrayal". The most common thing to see or especulate is that Guren ends up being possessed by Mahiru and ends up attacking others or perhaps that he might end up making an alliance with the first progenitor; even so, knowning Kagami, he's probably giving another direction towards this "betrayal". I could be wrong but well, this is a theory.
To begin with, let's start diving this huge theory in parts, first Guren and Mahiru's relationship; so far, their relationship is quite awkward but at the same time there's trust between them, there's love and sacrifice; therefore, what kind of relationship do they have?
Well, this will be in base to the Light Novel; which is the point on which everything started; Mahiru and Guren were two beings from different worlds; until someone decided to oppose or reject the decisions the first progenitor made against humanity; therefore that person decided to weaken the Hiragi family and after 500 years, that person ended up making two kids meet each other; that person is obviously Rigr Stafford. Even if he sought to divide even more the Hiragi family he never expected that love would bloom between them; therefore Guren and Mahiru started to meet up in secret until Tenri Hiragi discovered them and ended up separating them for 10 years.
After that, we know so far that Guren tried to look for Mahiru, he tried to understand her plans; he wanted to save her; even so, he couldn't grasp to a certain extend what Mahiru's plans were until he started looking up her research materials mainly because Mahiru left them specially for Guren to find out the truth slowly.
To give more focus on their relationship (not love but more like partners in crime, more like two souls that trusted each other) Guren and Mahiru trusted on each other in a way no one else does; even so, there was something that Mahiru never told Guren and that was her destiny; thaat she was living in order to die.
With this, Mahiru looked and experimented with the Hyakuya sect's help in order to give humanity the tools to fight the apocalypse or the catastrophe; just like making Guren and Shinoa survive the catastrophe; still, Mahiru never told Guren that she needed to die, that she needed to sacrifice herself thanks to a superior being and the fact that she only had someone who could call her family, that being Shinoa; Mahiru gave everything for her in order to make Shinoa live a "peaceful" life in a way the Hiragi family wouldn't bother with her lifestyle.
With this, Guren ended up wondering why he couldn't catch Mahiru no matter the effort he gave; and this is related with the previous parragraph, if Mahiru told Guren about her life, Guren would have done something worst in order to stop her from dying even so, if this had happened, Guren would have ended up dead.
Therefore, the relationship between both of them can be described as one of the purest even if the current Mahiru is a demon, there's trust; Mahiru is not a demon, she might be selfish but, there's something that lingers her to remain and keep herself from being a total careless demon. Now relating with the light novels; the reason why Mahiru killed Guren's friends...it is quite the dark story even so, if she didn't kill them, the JIDA would have killed them without mercy, therefore in order to leave Guren in peace, Mahiru ended up killing and commiting atrocities; and something the fandom tends to forget is that; before Mahiru died, she was a vampire, not a demon; she wasn't a namanari or anything; she was a sired vampire by the third progenitor Krul Tepes.
Now, with all of this, ¿what does Shinoa have to do with their relationship?
To begin with this, we know Mahiru loved Shinoa to no end; to the point she gave up her life with the sole purpose to allow Shinoa have a normal life, in order to make Shinoa have a certain amount of freedom or getting her rid of their own father, Tenri Hiragi. This is mainly because Tenri would have ended up using Shinoa as a human weapon if Mahiru didn't come up with plans or strategies. But focusing to the main point; Mahiru knew that she wasn't going to be able to give Shinoa the best future, because she knew that Shinoa's demon would return with her, therefore, Mahiru focused on teaching her sister how to close up her heart, how to hide her emotions even if it hurt; even so, there was a sole feeling Mahiru couldn't erase or erradicate, that being "love".
Why love?
Love is one of the feelings that holds a huge weight in the story; and this is mainly because it makes humans do a lot of actions, making them stop thiking about the danger, putting their lives at stake in order to reach their loved ones.
Even so, Mahiru knew that if Shinoa kept loving her or kept having this feeling for her; Shikama Doji would end up taking possession of her sister before she could grow up and develop; therefore, in the light novel when Kureto warned Guren about killing Shinoa; Mahiru told Kureto to do whatever he pleased, making Shinoa's feelings break into peaces and making her doubt about the truth of everyone's words.
Now, how does this affect Guren?
Guren was the 2nd person Shinoa trusted in; and this is mainly because so far, Shinoa didn't hold any affective feeling towards Guren even if she knew he was someone close to her sister; even though she knew Guren seeked to save her sister no matter what; at the same time, Mahiru shared secret information about Shinoa to Guren; giving as a result a certain amount of trust between Guren and Shinoa; asides from this, after the catastrophe, it could be expeculated that somehow Guren ended up taking care of Shinoa and this is mainly because Shinoa was used to live up by herself, therefore after the catastrophe, it can be said that she was left alone again; making Guren to check on her from time to time.
Returning to the main point; what's the eternal vow between Guren and Mahiru?
Their promise mainly focuses on giving hope to the human world; to the destroyed world, which means, they would follow up their schemes in order to restore humanity, even if they needed to commit dirty acts, betrayals and so on.
This can be proved mainly because of how Guren ends up making people turn around, making them feel confused and everything; mainly because he learnt this from Mahiru but also with the same reason he seeks to protect those he loves even if it means to hide the truth from them.
At the same time, that vow would focus as well on Mahiru's family, that being Shinoa; which means, no matter how hard the path was, they would find the way to put an end to everything.
Now, about that sacrifice, how does this relate with their eternal vow?
Guren is known as an anti-hero, which means he took the path of darkness with the sole purpose to see that glorious day; even so, Guren is tired, he has lost a lot of things mainly due to stuff of the past; and this is something we could see in chapter 56; Mahiru noticed that Guren's heart was at his limit, Guren couldn't stand holding the secret, seeing how time was running out.
Therefore, inside of that sacrifice; Guren will focus on reaching the place Rigr and Shikama are; that being said, Guren won't focus on killing Shikama, because even at the currrent time, Saito believes that Guren will be in Shinjuku; even so, their main focus is that, once Mahiru takes Guren's body, he'll find a way to have a short distance with the first progenitor; of course that'd surprise Shinya and company but, the result of this is with the sole purpose of one thing, to sacrifice everything in order to seal or at least to stop Shikama for a certain amount of time once again; meaning that Guren's body might end up being lost in the process.
Now, what does this suggest?
So far we know that Shikama is almost God, he was resting inside Tenri-s body until he died by Kureto-s hands< even when Mahiru was alive, she adquired or at least assimilated Shikama inside her body with the sole purpose to make Guren and her erradicate a certain amount of his part while the other was confined in a cursed gear; what does that mean? It means that Mahiru looked for a way to seal Shikama, that way he wouldn't be able to contact Shinoa easily; which is something that can be seen in chapter 73; since he wasn't able to enter in Shinoa's heart, he focused on another subject that he could invade.
Therefore, it's possible that Guren and Mahiru might end up facing Rigr, and after that, these two end up facing the first progenitor in a way to proceed to make a ritual or something similar to a seal in order to keep him restrained. On this point, it could be possible that Guren might end up losing a lot but at the same time, this will allow Mitsuba's squad to find a key to face up the first and finish up with Shinoa's possession.
With the sacrifice, is also possible that Guren might end up saying goodbye to Yu and even it might be possible that he ends up revealing how to save Shinoa in base of Mahiru's research.
What do you think?
This is based on canon stuff. I’m not focusing on any shipping attemp. Love is taken as a non romatic feeling but instead, a feeling that gives hope, kindness and friendship
