House Ravenwatch was a Second Era noble house based in the Rivenspire region of High Rock. Working under the guise of this status, the house secretly consisted of vampires who forsook their murderous ways and vowed to use their powers for good purpose. The house was a firm supporter of High King Emeric, who knew of their true nature.
House Ravenwatch was led by Count Verandis Ravenwatch, an Altmer pureblood vampire, who had been turned directly by Molag Bal. The house's base of operations was Ravenwatch Castle in Rivenspire, just above the town of Crestshade.
Members of the house lived by a code put in place by Count Verandis. It involved concepts of honor and vigilance, noble spirit and restraint. Their primary goal was to use their powers with responsibility, to help others. They were only allowed to feed on willing servants, never to excess, or on outlaws like bandits or cultists. They regularly trained to keep their vampiric urge to kill in control. The House was known to accept vampires who were willing to follow Verandis' code into their ranks. They also did historical research, and often worked to keep less peaceful vampires in check.
Known members of the house include the Khajiit Adusa-daro, the Wood Elf Gwendis, the Altmer Fennorian and the Breton Melina Cassel. The castle also housed a number of servants, who willingly let the members feed on them, and in return, their every need was tended to.
In the mid-Second Era, Count Verandis was friends with the Montclairs, one of the three noble families that ruled Rivenspire after Ranser's War. When Baroness Leila Montclair fell ill circa 2E 582 and was close to dying, her husband Wylon asked Verandis to turn her into a vampire to save her from death. Both Verandis and Leila refused, so Verandis used an Ayleid relic to cure her. Unfortunately, the relic was not powerful enough, and in time Leila's illness returned. Afterwards, Reezal-Jul, an Argonian in service of the Montclairs who secretly plotted to overthrow High King Emeric, manipulated Verandis and the Montclairs to look for a more powerful relic, known as "Abagandra", the Lightless Remnant. This artifact, resting within the great spire of Doomcrag, had been corrupted in ancient times, and it was corrupted further upon contact with Verandis. This resulted in all those present being turned into vampires, including the Montclairs. Baroness Leila did not want to live as a vampire and attacked Verandis, who was forced to kill her. This angered Wylon to the point that he decided to turn all the people of Rivenspire into bloodfiends through the use of the Lightless Remnant. Count Verandis felt great remorse for his involvement and issued a proclamation declaring his loyalty to the people of Rivenspire and King Emeric, as well as his desire to destroy the Lightless Remnant.
Along with Houses Tamrith and Dorell, Darien Gautier, and the Vestige, House Ravenwatch fought Montclairs' bloodfiends throughout Rivenspire, helped liberate upper Shornhelm and Northpoint, and eventually participated in a final confrontation at the Doomcrag where the Vestige killed Wylon Montclair. Unfortunately, Montclair managed to activate Abagandra's curse before he died, and Verandis was forced to strike a deal with Molag Bal, who agreed to take both him and the relic to Coldharbour. The people of Rivenspire were thus saved, and Adusa-daro became the new leader of House Ravenwatch. Shortly thereafter, Adusa and the Vestige defended the castle from an attack of assassins hired by Rohlbert, one of the remaining Montclairs, and later killed him, ending the Montclair threat for good.
After the disappearance of Verandis, the remaining members of House Ravenwatch decided to continue his legacy and kept living by the rules he had created. Several of those affected by the Lightless Remnant's blood-curse were thought to have found refuge with the house.
For game-specific information, see the ESO article.