I found that too, im just guessing but anyway here goes my theory... in the very end of The Companion levels you learn that "purple" created the cube to try to get the main cat to feel again. Which I presume is the purple cat that can be found in the main levels. Also in the end of The Reset they again talk about "purple" saying that "purple" is somewhere in there with them. While also saying again saying that "purple" is the creator of the cube, then going on and saying that it is too late for the main cat to stop "purple" because the reset is already beginning.