In Curse Of Strahd, Atlas Atruvian became witness to Vyacheslav's dark bargain through the Tome of Strahd. His cursed line eventually ended with the psycho-sadistic Viktor Vallakovich, who was killed during the Riots of the Blazing Sun. Vlacheslav's statue was subsequently brought down after the revolution, replaced by Fiona Wachter with a statue of Strahd himself.
The heir to the noble house Vallakovich, Vyacheslav was an ambitious and cunning manipulator and negotiator. His family had long established the bustling valley town of Vallaki, but after a century of torment by forces bearing the Mark of Strahd, the area had long been run down, with decreasing territory and a dwindling population. Vyacheslav used this state to cause the other noble houses in the town to submit to a singular Baron, promising them protection from Strahd von Zarovich. Unknown to his citizens, however, Vyacheslav ensured Vallaki's safety when he approached Castle Ravenloft himself.
After consolidating power in Vallaki under promises of safety and protection, he made an excursion to make a plea to the Vampire Lord, who welcomed him into the castle for dinner. Strahd had grown bored after terrorizing the town for over a hundred years, and sought other means of entertainment. Over their conversation, Strahd was impressed by the man, who was willing to sacrifice his future in order to achieve power. The Baron and the Count made a bargain: Strahd would let him live, and would not overtly meddle in the affairs of Vallaki. In exchange, the vampire lord cursed the Vallakovich line family line: every subsequent heir would be afflicted by increasing insanity.
The Baron took this deal, and ruled Vallaki with an increasingly iron fist. Under his rule, the town functionally became a police state, and he built the Vallaki Burgomaster's Mansion and erected a statue of himself in the Vallaki Town Square, though died from illness only a few years after. He was buried in the graveyard of Saint Andral's Church.