If asked about how he got his vampirism, Harkon will say how he once ruled as a mighty king, and that his domain was said to be vast and powerful. Despite all of this, his greatest fear was his own mortality, so he pledged himself to Molag Bal and in his name he sacrificed a thousand innocents. In return, Molag Bal granted him immortality by turning him and his family into pure-blood vampires. Due to historical contradictions with his story, it remains to be seen rather or not this story was at all exaggerated or just a downright lie made up to feed his large ego.
As the years passed and Harkon ran Volkihar, he uncovered a prophecy called the Tyranny of the Sun, that, if enacted, would blot out the sun and allow his kin to roam freely during the day. He started becoming obsessed with the prophecy and everything in his life, including his family, was pushed aside to try and make it a reality.
To enact the prophecy he required the ancient artifact called Auriel's Bow and the blood of a Daughter of Coldharbour. He would then put the blood on an Elven arrow and shoot it at the sun with the bow. Harkon wanted to use his daughter, Serana, as a source for the blood, as she is a Daughter of Coldharbour. His estranged wife Valerica saw how obsessed Harkon was becoming and disagreed with his goal. She believed that vampires should stay in the shadows otherwise it would bring too much attention to their kind, and that mortals would wipe out the vampires, attempting to bring the sun back.
In an attempt to stop him fulfilling the prophecy, Valerica locked Serana along with an Elder Scroll in Dimhollow Crypt for her protection and escaped to the Soul Cairn with the other scroll sometime before the events in Skyrim. Harkon, enraged by this betrayal, commanded every vampire in his court to look for them. After the Dragonborn finds Serana and brings her to Castle Volkihar, Harkon regains the confidence to continue his quest to fufill the prophecy.
Harkon is an elitist, and sees mortals as inferior beings. He has little regard even for his family, and only remembers his wife and daughter due to his lust for power, though he does seem to think that his actions are benefitting vampire kind. Harkon is cruel and will not let anything stop him in his quest for domination. He views the vampires found throughout the rest of Skyrim to be no more than feral animals that "frighten the herd" of mortal citizens of Skyrim that he and his fellow "pure-bloods" feed upon.
He harbors significant resentment towards his estranged wife, Valerica, and wished to enact revenge upon her for her betrayal. Similarly, Harkon holds a deep abhorrence for lycanthropes, considering the condition "filthy."
The Dragonborn first encounters Harkon upon returning Serana to Castle Volkihar after the quest Awakening. As a reward, he offers the Dragonborn the ability to become a Vampire Lord and join his clan of vampires. Alternatively, the Dragonborn can refuse his offer and fight with the Dawnguard against him.
If the Dragonborn sides with the vampires, Harkon sends the Dragonborn and Serana on a quest to find someone capable of reading the Elder Scroll. The two soon learn they need to find Dexion Evicus, a Moth Priest who can read Elder Scrolls, who's held up in Forebears' Holdout. After getting Dexion and bringing him back to the Castle, the Dragonborn learns that two additional Scrolls are needed to complete the prophecy. Harkon then sends the Dragonborn to find them, stating that they are located hidden with his wife Valerica and the other in some Dwarven ruins. After finding and deciphering the last two Elder Scrolls, the Dragonborn is finally sent to recover Auriel's Bow.
Eventually, the Dragonborn and Serana realize that Harkon's plan will doom vampires and mortals alike and decide to stop serving him. Once the three Elder Scrolls of Blood, Dragon, and Sun have been deciphered and Auriel's Bow has been gained in the quest "Touching the Sky," the Dragonborn and Serana go to Castle Volkihar to confront Harkon. After some dialogue, there is the option to either kill Harkon or give him the bow. Either way, Harkon begins the fight.
- Harkon's Sword
- Potion of Blood
- Vampire Royal Armor
- Vampire Boots
- Random enchanted or unenchanted jewelry
- One of many assorted random potions
- "You have forsaken my gift. The ancient blood no longer flows through your veins. Don't deny it! Count yourself fortunate that I'm a forgiving man. Now, be still while I give you the ancient blood once again." - If cured of Vampirism.
- "Yes, I can smell it on you. The power of my blood will purge that filth and make you whole again." - If the Dragonborn is a werewolf during their first conversation.
- You contracted a disease, perhaps, but you are no true vampire. Accept my gift and I promise that you will learn the difference. Refuse me, and I will banish you from this castle. I will spare your life this once, but after that, you are prey." - If the Dragonborn is a vampire during their first conversation.
- Despite Serana, Valerica, and Harkon being Vampire Lords, Harkon is the only one to visibly assume his vampire form.
- Harkon is one of three questline main characters in Skyrim that acts as a mentor to the Dragonborn (if the Volkihar Clan is chosen) and betrays them in the end, the others being Mercer Frey of the Thieves Guild and Astrid of the Dark Brotherhood.
- Miraak. Oddly, this is not the case for Serana, she only has one base ID and contains no follower dialogues. Harkon's character models are separated by four different base IDs, the first one is Harkon's humanoid form which is essential and contains no dialogue, the second one is Vampire Lord form which is non essential, the rest are hostile variants. This is for separating the character AI, the same feature is also shared by