The Creatures from the Sister World are a race of enigmatic beings hailing from a ringed world that orbits the unnamed planet in which Firefall takes place.
No much is known on what the beings from the Sister World look like, but according to Jacob Rowlin they possess a pair of large, black, almond-shaped eyes that seem to penetrate deep into the soul.
From the descriptions in the novel, the existence of the Creatures from the Sister World are know to the more primitive inhabitants of the neighboring planet. They are regarded as a mystery and are well know for their advances in the sciences. Strangely despite there being barely any contact with the two worlds, especially the more advanced society outside of Mure, the willots managed to arrange several meetings with the aliens. Through these transactions the willots traded three of their number to be allowed to access the Sister World's catalogs. From this they selected Jacob Rowlin to play the part of the Hur to fool the Lily People, in assisting them in liberating Mure from the degenerate rule of the Tower People.
After deliverance was given to both the Lily People and willots being freed from their shackles of enslavement by the Tower People, the end describes the Sister World being with satisfied with the results of their intervention.
From one of their contacts, Chesoon, the Creatures of the Sister World are recorders of information. They are described as meticulous record keepers and have actually documented each and every creature known to be in existence. For reasons unknown, they go to every world and systematically record every living thing in ridiculous detail: backgrounds, history, body chemistry, genes, etc. The creatures possess a vast catalog of exquisitely detailed information from each and every world without being seen. On some worlds, such as Earth they are responsible for several UFO sightings.
- Firefall by Marcus Malone (2011)