Black Spiral Dancers are Garou who have been corrupted by the Wyrm. The first Black Spirals were White Howlers, Garou from the British Isles. When the Pictish kinfolk of the Howlers were threatened, this tribe of Garou went deep into a Wyrmpit to try to find a way to drive back the corruption. Instead, they were theselves tempted and coerced into his service. The Howlers were made to walk an underground labyrinth where at every turn the Wyrm's minions accosted the Garou's very mind and spirit. Those that survived turned on the remaining White Howlers, forcing them to embrace the Wyrm or die.
Unfortunately, in modern times, most Black Spiral Dancers are Garou from other tribes who are tempted to the Wyrm's dark ways. The Wyrm and his minions have learned well the weaknesses of the Garou. Even an otherwise pure Garou can perform reprehensible acts if she falls into a Thrall Frenzy; many Black Spirals were tempted to fall by the destructive beast within. Others were ostracised or driven from the oft harsh mainstream of Garou society, and found in the Wyrm a willing patron.
The mindset and society of the Black Spiral Dancers is a twisted mockery of Garou society. They see destruction as their sacred duty, and corruption to be a sacrement thereunto. Many of their rites are similar to those of the Gaian Garou, but corrupted to honor the Wyrm instead. Black Spiral Dancers see torturing and killing humans as a time-honored pastime, and only maintain the veil to the degree that it keeps them free of retribution by humans and their allies.
Physically, Black Spiral Dancers are often twisted and grotesque. Those descended from the Howlers often have albino-white or grey-green fur, though the influx of corrupted garou of other bloodlines means that any coloration is possible. The Dancers make copious numbers of Metis, and even the 'pure' Black Spiral Dancers often have hideous mutations induced by Balefire and the Wyrm's vile investments.