Does the Other also exist in Echo? Is The Other what makes Echo Echo?
It really seemed like the other in Adastra was what was haunting Echo, so much dialog hints to it, a remnant older than our life a form of life incompatible with our own, that uses the minds of life to generate emotion it consumes, a great corrupting being that becomes a twisted form of lifes emotion and darkness without context of good or understanding of either.
it even seemed to explain all the routes in echo and echo tsr - the evil being transcends time and space able to manipulate multiple time lines, heck two of the routes in echo actually have dialog that implies the evil being is aware of choices made in a alternate time line (when a certain choice to kill a certain being results in the dialog "comes full circle") Even a time travel event that links echo tsr and echo together (too much spoilers to mention directly but it permeates in multiple timelines of both games)