At one point, I decided to see if I could figure out which of the conceptual strands identified, in the Ethereal Player's Guide, by David Edelstein and the artist formerly known as R. Sean Borgstrom are present in the ethereals from other supplements, based on what skills, Songs and other traits they display. I didn't completely finish the job, but I have frequent plans of getting back to it, and I've actually worked out reasonable strand-mixes for some of the Liber Servitorum characters. In some cases, I've even worked out what specific concepts, in an overall category, go to make up a given ethereal.
The Greys, for instance, are spirits of Fear (Emotions) and the Stars (Astronomical Concepts). Lucky the singing cigarette pack is a spirit of the Company (Society). Sophronia the sphinx is a spirit of Beasts (Life), Riddles (Information) and Wastelands (Terrain).
These are just my best guesses, mind, attempts at reverse-engineering the characters to fit rules that were introduced later. Other ideas are welcome, as are your guesses at what strands went into Bob's other contributions. (Even the ones that got cut.)
The Greys, for instance, are spirits of Fear (Emotions) and the Stars (Astronomical Concepts). Lucky the singing cigarette pack is a spirit of the Company (Society). Sophronia the sphinx is a spirit of Beasts (Life), Riddles (Information) and Wastelands (Terrain).
These are just my best guesses, mind, attempts at reverse-engineering the characters to fit rules that were introduced later. Other ideas are welcome, as are your guesses at what strands went into Bob's other contributions. (Even the ones that got cut.)