Prophet (Vampire)

Background
You now have the Elder Scroll, but you do not have anyone that can read it. The only ones able to read the Elder Scrolls are the followers of Cult of the Ancestor Moth. They are based in Cyrodiil at the White Gold Tower. At this time, you learn that one of the moth priests is visiting Skyrim and your mission is to find him.

Dawnguard Walkthrough

 * 1) Follow Isran. Talking to him allows you to help Gunmar track down vampires throughout Skyrim (Hide and Seek) and help Sorine find better crossbow technology (Ancient Technology).
 * 2) Speak to Serana.
 * 3) Speak to Isran.
 * 4) Locate the Moth Priest, Dexion Evicus.
 * 5) Ask Carriage drivers about the Moth Priest.
 * 6) Ask innkeepers about the Moth Priest.
 * 7) Visit the College of Winterhold to ask about the Moth Priest.
 * 8) Go to Dragon Bridge and talk to the guards or Clinton Lylvieve about the Moth Priest's location.
 * 9) Travel south across the Dragon Bridge. As you follow this path, you will eventually come across an ambushed carriage.
 * 10) Search the vampire for a note indicating that the Moth Priest was taken to Forebear's Holdout.
 * 11) Find the Weystone Focus on Malkus's corpse after killing him.
 * 12) Place the Weystone on the altar to deactivate the magic barrier.
 * 13) Rescue the Moth Priest, Dexion Evicus, who has turned hostile.
 * 14) Defeat Dexion, who will come to his senses.
 * 15) After talking to Dexion, he will head to Fort Dawnguard.
 * 16) Once at Fort Dawnguard, you must speak with Isran.
 * 17) Speak with Dexion, who will now read the Elder Scroll.

Vampire Walkthrough

 * 1) Follow Harkon and listen to his speech. He will ask everyone to go out and look for a Moth Priest that is visiting Skyrim. He tells you to ask innkeepers and carriage drivers located in Skyrim.
 * 2) Go to Dragon Bridge and talk to guards or Clinton Lylvieve about the Moth Priest's location.
 * 3) Travel south across the Dragon Bridge. As you follow this path, you will eventually come across an ambushed carriage.
 * 4) Search the vampire for a note indicating that the Moth Priest was taken to Forebears' Holdout.
 * 5) Find the Weystone Focus on Malkus's corpse after killing him.
 * 6) Place the Weystone in the altar to deactivate the magic barrier.
 * 7) Rescue the moth priest, Dexion Evicus, who has turned hostile.
 * 8) Defeat Dexion, who will come to his senses.

Bugs

 * When you go to save the Moth Priest, he may be outside of the magic barrier. If he is, then do not deactivate the magic barrier. If you do, he will stay down after being defeated. Every time you enter Fort Dawnguard or Castle Volkihar, he will attack everyone. The only workaround at this time is loading a previous save.
 * Guards do not run through quest script and cannot be interacted with beyond their usual script.
 * Solution: Bypass the need for speaking to the guards by going south out of Dragon Bridge to find the ambushed caravan.
 * Also, talking to Clinton Lylvieve will advance the quest and mark the ambushed caravan on the map.