Vorobei

Vorobei is a servant of Dazhbog, but one who believes that members of the Old Faith and the New can abide one another. He came to Vladykino to seek out Yuri Barolov, and happened to arrive on the day of his wedding to Svetlana. Nil, an older hermit who is present there, recommends Vorobei as Yuri's guide on his path to becoming a bogatyr. 
Vorobei promptly got drunk at the wedding, and proceeded to harangue Kolovul - a marauding wolf shapechanger who broke into the village during the festivities, about Dazhbog and the God of the Gaalites being one. Kolovul - a servant of Grey Wolf - an entity gathering wolves and other beings to him to reclaim lands they once ruled rejected his entreaties, and called him a traitor - the Children of Dazhbog had betrayed the Children of Darkness, and their own heritage as well, he told him.
The following day, though nursing a hangover, Vorobei agreed to guide Yuri and the rest of the Serpent Slayers into a some nearby caves where, according to legend, the bogatyrs of old lie sleeping. He was recommended for this role by Nil, and Yuri, though skeptical, agreed. Vorobei's glowing face lit up the darkness, and he guided his new companions through the dark tunnel. He could not make sense of what looked to be a Doomstone at a parting of three ways, but, after transforming into a hawk, he flew down the long middle tunnel, and discovered a huge chamber filled with bones, and a rickety rope bridge suspended above it. He then explored the left-hand tunnel, and found another chamber wherein burns a ring of fire. A haunting singing emanated from inside the ring. When Vorobei returned to the intersection, another of his new companions, Agapia, recalled that the Doomstone was likely a marker put in front of bogatyrs - if the travel left, they find a spouse, right - a horse, and straight - their death. Already being married, and not being ready for death quite yet, Yuri proceeded down the right tunnel, and whistled. A bogatyr's horse came trotting out to him, followed by some huge wolves on its heels. The wolves were defeated quickly, though they did come near to tearing Vorobei limb from limb. The survivors fled, and after following them, Vorobei's companions found a chamber with a stone horse, a huge mother wolf (which they cowed into submission), and a pair of gold and silver dippers, curiously suspended from a cave ceiling.   
After Lokan - another of the new companions - procured these, the party returned to the Doomstone. But the way out of the caves was blocked now, so they proceeded to the middle passage, which was lit up by a mysterious glow. Agapia felt a great evil there, however, and the party returns to explore the left passage, to learn about the ring of fire and the haunting singing, though no one was interested in marriage at this time. Vorobei transformed back into a hawk, and flew over the ring, where he beheld a silken tent.  
Suddenly, he returned, and turned on his new companions. They held him back and advanced into the chamber. A woman with dark, shadowy wings emerged, flying over the wall. She apparently released Vorobei from her spell, and turned on Yuri. Humiliated and offended, Vorobei changed back into a hawk, and headed toward the exit. 
He has not been seen by the Serpent Slayers since.