the white poison belongs outside the frame of the story - the candy corn on the website header, the blank background, the white door. only when taken inside canon does it become toxic to the narrative itself. likewise, the black poison belongs to the frame of the story - the black void of the furthest ring. when taken out of the story into fanfiction (the epilogues), it becomes poisonous to the characters there

This is definitely one possibility worth considering!

I wonder if it says anything about the nature of Homestuck’s “meta-villains”? If evil characters like Doc Scratch exist “closer to the surface of the story’s meta-bubble,” would the opposite, benevolent version of this be a character who lives outside of the story, but close to the narrative itself? Like an author or a reader with interactive abilities?