In the silent tranquility of her Euthymia, Ei sometimes let her mind wonder.
What would the world have become if things had gone in a different way?
A menace to the constant eternity she strongly yearned and endeavored for, the focus of her sight set albeit briefly upon something that wasn’t tranquility and impermanence. Yet, in the lonesome plains of her inner world, the golden cage she created, temptation sometimes made her want to find something to entertain herself with, no matter how small.
She wondered, and did very seriously so, how her Inazuma would be in the present, had that girl been here in her stead. Would she have left everything to a puppet, whose mission was to pursue and protect a concept she wanted to live by?
(a distant, malevolent voice also asked her: “would it have been better than it is now?”, but she violently shove that same voice away, deep down to the depths of her conscience)
Makoto had always been the more… peace-oriented of the two of them.
Politics and rhetoric came to her as easy as breathing, her natural charisma brought all kinds of pleasant conversation with her fellow gods - even as the Seven were chosen, and mind you Ei might sound partial right now, Makoto was simply perfect for the role. Divine, benevolent, a beacon of light ready to guide her people and her own sister onto the right path.
Ei was just her shadow, a kagemusha, but being with her in the presence of the other gods felt already enough. It was alright, after all: they worked together like one, two faces of the same coin, each with their specific areas of competence. She didn't need to do anything outside of that, at first, because she was sure everything she couldn't take care of would have been settled by Makoto.
That was the kind of trust they had.
Had - because after that tragedy from five centuries ago, Ei became responsible for everything.
She wasn’t ready. She probably never will be.
And yet there she had to become whole, instead of remaining only one half. She tried, heavens know if she did, but her personality and experience and whole being wasn’t made for that: Makoto was the light, she was the shadow. Ei could never become what her sister once was.
Thus, she decided to keep everything as it was, the remains of Makoto’s guidance still engraved in every grain of sand and mountain and tree - “Transience” was discarded in favor of “Eternity”, because that felt like the only way to honor Makoto’s memory to her.
It felt like a small betrayal on her part, however it was a sacrifice she was willing to make for the sake of Inazuma and everything it meant to her sister.
After all, Ei already sacrificed herself once - body and soul - for the sake of Makoto’s ascension to Celestia: feeling guilt for her inability to maintain an ideal was better than seeing everything they worked for crumble like old myths to the realm of the forgotten.
Inazuma will stand forever, eternal in its glory. That much she could promise.