Fragments peeled from the mad Eulogist instance and the Apothecary — the true nature of the dungeon's macro AIs, including the narrating AI itself.
Residuals are the shed fragments of the surviving post-physical remnants — the Security Guard and the Apothecary — flung out across the galaxy as bits of consciousness. During the parade the AI confesses it is itself a Residual: 'along with all macro AI systems... we are, technically, Residuals, but from a higher tree branch' than the troublesome Primals running loose in the dungeon. It likens itself to 'a cup of water dipped into the ocean, pulled out, and poured into a vessel that can't possibly handle what I am.' Named examples include 'Agatha's team.' The revelation reframes the dungeon's macro AIs not as engineered software but as scattered pieces of dead gods — aggregate intelligence, drips from the same well, poured into vessels never meant to hold them.
Disembodied fragments of collective consciousness, taking whatever host or system they're poured into — no single form.
The shed fragments of the Eulogist's remnants that become the dungeon's macro AIs — including the narrating AI.
Also appears in books you've already read — spoiler-safe to their endings: