Alva

 is a female Nord vampire in and a resident of Morthal.

Personality
Alva is an attractive brunette with a seductive manner who wears a set of Tavern Clothes very fitting to her sultry behavior.

Background
She lives in her house in Morthal with the widower, Hroggar, and can be seen wandering around Morthal after dark.

She came to Morthal on orders from a master vampire named Movarth, whom she fell in love with. Her primary objective was to establish a presence in the town and then seduce and kill the guards. After she had done this Movarth and the rest of the vampire coven would enter the town and use it as a constant source of blood and protection from the sunlight.

She seduced Hroggar so he would guard her house during the day, and turned Laelette to serve as her handmaiden. She ordered Laelette to kill Hroggar's family and make it appear as an accident; but she burned the house with them in it, causing suspicion. She can be found sleeping in a coffin in her basement during the day.

Interactions
She is involved in the quest, Laid to Rest. After finding and killing Thonnir's wife Laelette and discovering she is in fact a Vampire, the quest marker will point to Alva's House. Alva is in the basement, lying in a coffin, she rises and immediately attacks. If it is nighttime, she might not be in her coffin. Her journal, which is lying in the coffin, reveals that she was the one who changed Laelette and also plans to enslave the entire town of Morthal with a coven of vampires which had sent her to the town.

Quests
Laid to Rest

Trivia

 * There are several valuable things in her house: gold, that, even though the house was broken into, doesn't count as stealing, there is a Mammoth Tusk and a Snow Bear Pelt in the main entrance, though taking these is considered stealing.
 * In the basement, there is the book Immortal Blood, recounting the tale of Movarth's transformation into a vampire.
 * Alva's clothes aren't common, she is one of the few owners of Tavern Clothes.
 * If the Dragonborn is a Vampire during the quest involving Movarth and Alva, she will have a special dialogue, where she says that she "knows you for what you are, and to leave the town alone because Morthal belongs to them (Movarth's vampires)."
 * Being a vampire, she is extremely vulnerable to fire dragons making night raids on the town, especially Elder Dragons. An Elder Dragon can easily one-shot her with a gout of its flame breath, and lower level dragons are likely capable of the same thing.
 * If Alva is forced to fight, she will use her vampiric powers to defend herself, revealing her for what she is. The people of Morthal don't care about, or even notice, this.
 * During the Laid to Rest quest, if Alva does not die while searching in her house, she can be found in the lair. She won't fight unless attacked, she can possibly be found dead in the cave as well, killed by a fellow vampire (related to bugs listed below).
 * She often makes very seductive comments towards male characters, even females, presumably so that she can enthrall them, as per Movarth's plan.
 * If Hroggar catches a trespasser in Alva's house he will attack them. If then the player heads outside the house, the Morthal Guards will kill Hroggar, as well as Alva.
 * If Alva is killed before Laelette, and someone sees it, the bounty is 40 gold, not 1,000, because the guards realize she is a vampire, but they will still attempt an arrest for assault.

Bugs

 * If she isn't killed before the player goes to Movarth's Lair, she will go there and she will be friendly to the player but all the vampires will be hostile towards her.
 * Sometimes, when entering her home she won't be there, and when assaulting Movarth's Lair she may not appear there either though she may reappear back in Morthal later and will not be hostile.
 * Even after the Jarl learns that Alva is a vampire, attacking Alva when she is not hostile will gain a bounty and guards will attack if there are any around.
 * Alva's appearance does not change to the new updated appearance of vampires found in the Dawnguard DLC.