The bodies lie below. Paper-thin parchment skulls and wasted uneaten limbs. Rare to see abandoned flesh unused. The butterfly’s throng the walls. The blue is giving you waves of euphoric sorrow. A tragidean high like heroes feel before the axe comes down. If you look to closely at the butterfly wings, gaze the unending edge, your bloodvessels will crimp and burst in your head. The butterflys will eat your eyes and nest inside.
If one flits across your yellow-white light it looks like the shadow of a butterfly caught on a wall, but alive, pressed in living dimensions and pinned, momentarily, in mid-air.
The freshly-dead heads are burning. A soft, dim low-light infra-red, emitted from the mouth and sunken eyes. Like a coal glowing in an empty skull. A blood-clot ruby red. A dead-star-red.
Inside are jewels. Pick-up the skull and turn. Ignore the tears streaming from your eyes. Ignore the petrified childhood dreads cracking their coverings in the back of your head. It's just the butterfly’s bipolar-blue-glow. Inside the empty head, eaten out, they lay their chrysalids. Glimmering ruby-bright lozenges, irregular jewels. At their centres, knots, vaguely pulsing tangles of slight light. The jewels defend themselves with lust. Designed to drive a predator to unexpected doom, they embue anyone touching them with crazed, gothic self-destructive horny lust for any available partner. Be careful when you pick them up.
The caterpillars that will hatch from these glimmering seeds are jewels themselves. Perfect segmented prismatic rainbows of liquid light. Magnificent luxurious slowly ambulatory gem-beasts. Twisting and turning curlicues upon themselves.
The bite of the magnificent caterpillar is the most dangerous and sacred of all. A madness-bite. Instant schizophrenia.
These insects are immeasurably valuable and dangerous at every stage of their development. Much sought by decadent deep-dwelling peoples.
Many a throne-room, netted with silken silver nets, is lit with the butterfly's death-dark blue. Less a colour, almost a living liquid that sloshes immeasurably slowly from surface to surface. It's long looping wavelengths almost fingertip tangible.
The butterfly's blues light causes bipolar behaviour. Mood swings, mania and depressions. The kind of nobles that willing fill their arbours with this blue either don't notice, don't care, or actively enjoy the results. They believe deeply that the butterfly’s can sense noble blood*. More than one feud has begun when two nobles pricked their fingers in the butterfly room and waited, with dark blood beading on their outstretched hands, waiting to see where the first butterfly would land to feed.
The fact that looking closely at the butterfly's wing can kill you in one stroke is considered a handy shibboleth. Keeps the scum out.
The chrysalids are worn as pervy jewels and used as drugs, for obvious purposes.
The liquid-crystal-caterpillars are the most prized of all. Schizophrenia, amongst it's drawbacks, sharpens some aspects of pattern recognition and heightens the threat-sense. For normal people the horrific life-damage done by even temporary madness makes it a poor deal. For the murderous rulers of knife-edge subterranean states, things are a little different.
In a world where almost everyone you know is probably plotting against you to some extent, believing yourself to be under threat is less of a hardship. The obsessive correlating of the tiniest tangential evidence, the half-sensed look, the sly event, into tangled webs of paranoia, this is actually useful. Those webs really do exist. They really are trying to kill you. Being crazy about it just lends you energy and perception. Another advantage is that deranged bouts of terror-strewn violence, random executions, wild accusations and frantic source-less witch-hunts keeps everyone in the right state of apprehensive fear. If a normal person goes crazy, they fuck up their own life. If a tyrant goes crazy, they fuck up everyone's life.
Being known for occasional periodic violent insanity can be handy for a rulers reputation.
They wear them as living earrings. This has created a fashion in Drow society. Fake costume-jewellery crystal caterpillars. (The trick is to look for the tiny scars on the nape of the neck.)