Should I Refuse Lord Harkon?
If You Exit the Conversation When Lord Harkon Tells You to Make Your Choice, and Take Too Long to Give an Answer, He Will Banish You from the Castle as If You...
If you exit the conversation when Lord Harkon tells you to make your choice, and take too long to give an answer, he will banish you from the castle as if you chose to refuse his gift. If you are a werewolf, siding with Lord Harkon will cure your lycanthropy. ... You can restore your lycanthropy this way only once.
Should I side with the vampires or Dawnguard?
Overall, the physical rewards (weapons, etc) are better if you choose Dawnguard. However, you cannot regularly use the powerful Vampire Lord form until after you've completed the main questline, or else the Dawnguard members will not accept you.
Is Lord Harkon bad?
Type of Villain
Lord Harkon is the main antagonist and final boss of the Dawnguard DLC for the 2011 role-playing video game The Elder Scrolls V: Skyrim. He is a Nord vampire and the oppressive leader of the Volkihar Clan, a powerful vampire family.