Radanavich
"Live you always among monsters, and see everyone you love die beneath their claws!"
- – Madame Irena Radanavich, cursing Rudolph Van Richten with her dying breath.
"Undead take you all, just as you have taken my son!"
- – Rudolph Van Richten, cursing the Radanaviches in fury for their having kidnapped and sold his only son to a vampire.
The Radanaviches are a minor yet important element in the backstory of the Ravenloft setting for Dungeons & Dragons, having been essential to the backstory of the iconic NPC Van Richten and his subsequent story in the game's lore.
Originally, the Radanaviches were a Vistani clan belonging to the Corvara tribe, a sect of Vistani who are particularly infamous for their tendency to rely on a life of thievery, cheating and deception. But the Radanaviches were on the shadier side of the moral spectrum even for the Corvara, and this spelled their doom when the clan's raunie (matriarch and seer), Madame Irena Radanavich, chose to hire the clan's services to a vampire named Baron Metus. The Baron, you see, was looking for a comely human youth to become his "groom" - a special form of vampire created through ritualistic spawning, imbuing them with a telepathic link to their progenitor and unusually rapid development of vampiric powers. As he promised the Radanaviches a great sum of money for this task, the clan agreed, and tried to kidnap the son of another noble family from somewhere in Darkon. Unfortunately, this went terribly wrong; the baron's family was well-guarded, and in the fight, not only were the Radanaviches forced to flee, but Madame Irena's son Radovan was mortally wounded.
Desperate to save Radovan's life, the Radanaviches invaded the home of Van Richten and demanded he operate. But Radovan's injuries were too severe even for Van Richten to stabilize, and the Vistani died on the operating table. Madame Irena flew into a mad rage, accusing Van Richten of deliberately sabotaging her son's operations, and the terrified doctor pleaded with the Vistani for mercy, offering them whatever they wanted if only they would spare his life, at the time having only heard rumours (but not the truth) about the terrible curses that Vistani could level against targets of their ire.
So they kidnapped Van Richten's son Erasmus and fled with him. But they severely underestimated Van Richten's paternal instincts; despite his fear of the Vistani, the doctor's fear for his son's life caused him to give chase on horseback... and then, in the mother of all Random Encounter Table dickery, he ran into a mob of undead who would have slain him had the lich Azalin, Darklord of Darkon, not intervened and taken control of Van Richten's would-be devourers to find out what was driving this particular subject of his on a long and mad ride. Not possessed of any great love for the Vistani, Azalin for his own reasons (mainly because it amused him) listened to the doctor's story and decided to aid the grieving doctor; he animated Radovan's corpse and compelled it to lead Van Richten to his former peoples' new camp. He also gave Van Richten a magical ward against the undead, which protected Van Richten as a small army of zombies began to gather around him in his defense.
When Van Richten finally caught up to the Radanaviches, he threatened to unleash the zombies on them unless they returned his son. Madame Irena decided the best thing to do when confronted by a scared, angry father in full familial protection mode and leading an army of zombies was to mock him, taunting him with the fact she had sold his beloved Erasmus to be a gay vampire's sex slave, perhaps trusting too much in her people's longstanding protection against the undead and not knowing that terrible forces were closely watching the drama unfold. Not surprisingly, Van Richten snapped; he went insane with fury and set the zombies on the Vistani, condemning them all (or so he thought) to a horrifying death their own powers were useless to prevent (for reasons discussed below). In her last living moments, Madame Irena, completely refusing to accept that she'd brought this on herself, cursed Van Richten to forever suffer the tragic losses of his friends at the hands of monsters, but did not count on an enraged Van Richten returning a lethal curse of his own (see the second page topquote), a curse that was, unbeknownst to him, given life by the Dark Powers themselves, and showing too late to the Radanaviches that Vistani themselves were no more resistant to curses than anyone else and that the Dark Powers don't play favourites. In fairness, he did snap out of his fury and tried to stop the massacre, but the zombies wouldn't listen. The only Vistani survivor of that fateful night was a young boy named Arturi Radanavich.
Upon reaching Baron Metus' estate, Van Richten was refused entry, but his son sneaked out to meet him, sadly already transformed into a vampire, but still retaining enough freedom of will to request that his father free him from undeath at the point of a stake and sunlight. Van Richten tearfully did so and returned home to Darkon, only to discover that his wife had been killed by Baron Metus in retribution, something that solidified his decision to become a monster hunter. Decades later, he would meet the grown Arturi, and learn of the fact he had been laboring under Madame Irena's Vistani curse all his adventuring career. With Arturi as his guide, Van Richten came to learn about Vistani culture, and to realize that they weren't all as evil as the Radanaviches, causing him to relinquish his hatred against the Vistani and lift his curse from Arturi, who in turn lifted Madame Irena's curse from Van Richten. This tale forms the backstory to the splatbook "Van Richten's Guide to the Vistani".
But that wouldn't be the end of Van Richten's encounters with the Radanaviches. As recounted in the adventure Bleak House, Madame Irena's vengeful spirit would return from the grave as a ghost, determined to end Van Richten, alongside the ghost of her son Radovan. This ultimately resulted in their final destruction.
As for the last survivor Arturi Radanavich, his ultimate fate is not recorded. Though the final parting between Van Richten and Arturi was a friendly one and Van Richten suggested that Arturi resume his former life with his tribespeople the Corvara, Arturi sadly replied that he was "no longer Corvara" (perhaps having relied too long on the kindness of non-Vistani strangers during his decades on the run to consider returning to a life of cheating and deceiving them) and that his fate was still to wander the domains as an outcast, even without the undead at his heels. Even if he did go back on his word and rejoin his kinsmen, a Vistani man always marries into the bride's family, exchanging his surname for hers, so the Radanavich name (if not necessarily Radanavich blood) was doomed to extinction anyway. It is likely that Arturi's fate was left open for DMs to pick up on, whether for Arturi to act as a guide for PCs, or a source of information, or even to turn his back on his Vistani heritage and lose his powers by claiming a permanent, non-mobile home (becoming mortu or "half-dead" in Vistani parlance).
In Dungeons & Dragons 5th Edition, after seeing too many people slamming Curse of Strahd for its "racist" Vistani, WotC chose to retcon the Radanaviches from Vistani to a human trafficking ring who merely disguised themselves as Vistani to try and reduce the efforts to repel them by sheer fear of the Vistani's reputation.