Just wanted to add to your observations about the poison that 1. John ends up "hosting English" in Candy as well, with Jake living at his house and 2. it remains odd that WV's first words to John in the Medium (BOY. YOU THERE, BOY. QUIT ALL THIS SCURRYING AROUND) get repeated almost verbatim when Lord English first speaks.

Good observations! Probably worth noting is that when they dwell together, Jake and John partake in a bottle of whiskey together; i.e., Jake brings poison into John’s home. Scenes involving alcohol in the Epilogues seem mostly concentrated around Jake, in fact.

Lord English has always had an intriguing relationship with the exiles concept, between Caliborn inhabiting an exile station during the final stretch of Homestuck and Lord English inexplicably keeping Karkat’s exile station locked away in a vault deep within his mansion. If English himself is connected to the forces that control the characters, it only stands to reason that he might ultimately take control over the protagonist of the story.