The project metastasized. Its new protagonist, Ceann (voiced by Mitchell), is the man Mitchell might have become if he had never left Junction City, Kan. (Mitchell described Ceann as “a dangerous liberal shut-in,” adding, “But doesn’t everybody feel like a dangerous shut-in lately?”) Still, there are Hedwig shout-outs: Ceann lives in the vintage double-wide Hedwig once rented. “The bathtub still coughs up blond wig hairs,” he says in the first episode. Because Ceann has a brain tumor — another angry inch? — and no insurance, he creates an online telethon to raise money for his treatment, singing his life story to anyone who clicks.

Like Ceann’s telethon, “Homunculus” addresses private pain in a public medium, enfolding, in ways that are more and less fictional, the deaths of Mitchell’s younger brother, former boyfriend and father, as well as his mother’s Alzheimer’s disease. “The whole piece is me dealing with loss,” he said. When a script had been drafted, Mitchell realized he didn’t want to put it onstage. “At some point, I was like, ‘How do I do this eight shows a week?’”

He figured it might work as a TV series. Hollywood executives disagreed. (“I could always see them glazing over, going, ‘There’s no way this fits into our metrics,’” Mitchell said.) But Topic, the entertainment arm of First Look Media, had been looking to finance a new narrative podcast, and gravitated to the pitch. “The concept would be a magnet for the kind of talent that transcends what’s been done in podcasts to date,” Michael Bloom, the C.E.O. of Topic and First Look Media, said in an email.

So Mitchell got to work again, converting visual elements into aural ones — writing lines in place of reaction shots, making soundscapes do the work of sets.

He also composed a casting wish list. Most of those wishes were granted. “I would walk with John to the ends of the earth,” LuPone wrote in an email. “In this case, I only had to stand in front of a mic in my slippers.” (She plays Ceann’s aunt, a nun who dies of AIDS-related complications and also sings a fast jazz number.)

Mitchell sent lyrics to Weller, who sent them back as ballads, bebop, slow jams, Brazilian tropicalia. Close, who plays Ceann’s mother, sings a thrash metal number.

“Yes! Blow that mic!” Mitchell said when Close, with her dog, Pip, at her feet, recorded the song “Dissolve Me” last spring.