I finished up Flight from Neveryon on Sunday. The last part of the volume is The Tale of Plagues and Carnivals a novel from 1984 that is considered the first about the (at that point) emerging AIDS crisis. As an active gay man in New York City at the time, Delany brings autobiography into the novel. The narrative shifts between telling of a sexually transmitted plague in Neveryon, fictionalized autobiography about Delany and some acquaintances in contemporary New York City, and outright essayistic commentary both about the writing/novel and the disease. To the new reader it can be a bit of a jarring shift from the previous parts of the series, though not totally unexpected, as all the volumes also include various pre and post matter relating the stories both to Delany as a character/author and a related (fictional, but... set in the "real world") scholar who translates a (fictonal) ancient manuscript that Delany supposedly used as a basis for the setting/stories.
But with this novel, the "real world" intermingles with the sword & sorcery world at various levels. Not just the insertion of the narrative about Delany in NYC during the early days of AIDS, but also characters crossing between the two worlds. There are still long sections solely based in the fantasy world, that, as I suspected but didn't recall earlier, bring the "Master" who was the unheard recipient of the monologue in the previous story. Various (most? all?) of the characters from the previous stories also make smaller (subtler) or larger appearances throughout. In two important sections, we see people misinterpreting events from previous stories, a common theme throughout the series, as the interpreters make use of information to prove their views and are either naively or willfully ignorant of what goes against them.
In multiple postscripts from subsequent editions, Delany updates his information about AIDS, with quite a bit of information that can be surprising. In particular the very limited number of studies to understand how people actually got the HIV virus sexually (blood transfusions and sharing needles being much clearer methods). It is perhaps too a propos to be reading that as the world is enduring this current pandemic. At one point in the novel, when the source of AIDS, HIV, is discovered, it is announced that they think medical science is 2 years away from a vaccine. That was 1984. 36 years ago now.