The castle itself a character? Yes. Above and around all the other characters, its corridors and halls are more than just a background against which their lives are played out, it is a chief player itself, with its history, its ancient rituals.
"Withdrawn and ruinous it broods in umbra: the immemorial masonry: the towers, the tracts. Is all corroding? No. Through an avenue of spires a zephyr floats; a bird whistles; a freshet bears away from a choked river. Deep in a fist of stone a doll's hand wriggles, warm rebellious on the frozen palm. A shadow shifts its length. A spider stirs...
And darkness winds between the characters."