Although the Character Development Threads don't have an official plot, there's always the mystery of why all the characters are meeting...and more.
The Nature of the Threads
It is a dream.
The Tropers are behind it.
Haruhi Suzumiya is behind it.
Master Hand is behind it.
QQQQQ is behind it.
Chihuahua0 is behind Beach House, Castle, and Carnival.
Here, writers and thread spectators alike can add WMG entries pertaining to the characters of their fellow writers and CDTers. (Though writers may opt out of having WMGs if they so wish and are free to comment on entries made for their own characters, writers should refrain from adding entries for their own characters.)
Quon is aware of what is going on.