Disclaimer: KnM? Not mine.
Who's Insane?
Chikane was insane.
Himeko didn't believe that though, she'd clung to the fact that Chikane was perfect; she was smart, beautiful and kind, she would never destroy the world were she given a chance to. It was shameful of her to think this, but Himeko completely trusts Chikane's ability to make her happy when she's sad. She would always expect Chikane to be always there to protect her (Himeko had forgotten about Souma).
Himeko loved Chikane.
She would grant her deepest desires, making sure she was happy too, because that was what Chikane had done for her. Though Himeko was sure that even if Chikane ignored hershe would still do the same things for her.
So, if Chikane wanted to die, Himeko would allow that. If Chikane wanted Himeko to kill her, HImeko would grant that wish. After all, everything that mattered were Chikane's wishes, Chikane's happiness.
And as Chikane dies in her arms, Himeko apologizes for having done such a terrible thing. Himeko cries because she killed Chikane.
But deep down Himeko was happy for having grant Chikane eternal bliss.
A/N: Hey lol, don't get me wrong here, I love KnM, but I'm a person who enjoys working with insanity. Somewhat inspired by Darkauthor26's one-shot ATLA(Avatar the Last Airbender) fics. You should read her works, they're awesome.