Some people in the Puzzlebox don't seem to be real in the same way others are.
Is anything real?
Some places or factions make distinctions (which they may consider quite firm and objective, even if others find them mostly or wholly subjective) between reality and virtual reality and dreamspace or unreality. Up tends to emphasize this distinction despite (or perhaps because of) widespread use of educational, therapeutic and recreational VR. On the other hand, the Ephemeralis in Bottom is largely predicated on the lack of a clear line between 'real' and 'unreal' reality. And, for instance, the Quartz Lyceum of the Glorious Constellation in Top studies dreamspace as more real than so-called waking life.