Domains of Dread

The Demiplane of Dread, commonly known as Ravenloft, was unique, similar to the plane that contained the city of Union in that many worlds and planes connected to it but it was still independent of them all. It was technically part of the Ethereal Plane but was markedly different from the vast majority of that place. Someone on the demiplane would be forgiven for thinking that it was made out of some supernatural mist as the stuff bordered every domain and entering the mists could transport one to another location on the demiplane. These mists occasionally formed on the Material Plane to bring individuals, buildings and even entire countries into the demiplane.

The Demiplane of Dread was controlled by the almost completely unknown Dark Powers and sections of the demiplane were ruled over by Darklords. The Powers had no goals that anyone can confirm but seemed attracted to people and creatures that committed evil acts or suffered from some terrible loss. They regularly inflicted despair on the residents of the demiplane by simultaneously granting them boons and inflicting curses. Each curse was tailored to the individual and inflicted the greatest amount of emotional harm or distress upon them. This often spurred those individuals to commit greater acts of evil. It was apparent that the more heinous the deed, the greater the power and the worse the curse granted/inflicted upon the individual until a new land was generated on the demiplane and the individual was trapped forever within that land. These individuals became the Darklords and they could never leave their domains whereas others may be able to leave but only if they have no great desire to as the powers almost always intervene to dash the hopes of those trapped within their realm.

When Shar created the Shadowfell, the Demiplane of Dread fragmented and each Darklord's realm settled into a spot somewhere within the newly created plane, possibly attracted by the plane's sinister nature. Within the Shadowfell, these realms became known as the Domains of Dread. Despite Shar's dominance of the Shadowfell, the Dark Powers still had control over each of these Domains.

In relation to the Forgotten Realms, Castle Spulzeer in Tethyr was sucked into the demiplane by a magical gem set in the hilt of the dagger Aggarath. Jander Sunstar suffered a similar fate after he swore revenge for his dead love, and the Lost King of Cormyr, Gondegal, has gained a position of power as the leader of the Knight of the Shadows order, a secret society dedicated to the protection of the helpless and oppressed.

Several residents of Faerûn have even risen to the level of Darklord. Harkon Lukas the cormyrian wolfwere, Hazlik, a red wizard, Urik von Kharkov, an escaped magical experiment, Draga Saltbiter, a Sword Coast pirate turned wereshark and Tsien Chiang the reknowned sorceress from Kara-Tur.

Barovia
Of particular note is the Domain of Dread known as Barovia. This shrouded valley has had several documented visitors from Faerûn, including the aforementioned Jander Sunstar as well as Minsc, Delina, Krydle, Shandie, a Kelemvorite paladin named Nerys and the famed explorer Volo. Tatyana Federovna, the woman who caused the domain's Darklord, Strahd von Zarovich, enough anguish for the domain to be created in the first place, came from Barovia to Faerûn, as did several of Strahd's servants looking for a locket that also originated in Barovia. The Svalich Woods of Barovia also briefly merged with the Quivering Forest and Twilight Marsh near Phlan in the late 15th century DR. The Vistani nomads of Barovia were known to frequent parts of Faerûn and shared similarities with some Gur, suggesting that the two peoples may be related.

Before it became part of the Demiplane of Dread, one of the two gods worshipped in Barovia was Lathander, though he no longer had any power there after the rise of Strahd, and didn't answer the prayers of his few remaining followers, who remembered only his title of Morninglord since his name has been almost completely forgotten over the centuries of his silence.