In Dan's novella "Flashback" and later in the novel of the same name we have the first mentions of the drug that later is in the HYPERION universe.
In the novel FLASHBACK we have mention of the Joe Kurtz novels/movies in which he is a fictional character showing up in this universe with Soul Dad, a character that is also in THE HOLLOW MAN.
Then we have the main character from BLACK HILLS, Paha Sapa, also being in Dan's novel THE FIFTH HEART.
All this ties in with aspects of THE HOLLOW MAN, ILIUM/OLYMPOS and the stories, "Madame Bovary C'est Moi” and "Vanni Fucci Is Alive and Well and Living In Hell”.
If I'm remembering this stuff accurately that is…
Words can't define what I feel inside
Who needs them? -- Smashing Pumpkins "GEEK U.S.A."