- Talk to Esbern or Delphine.
- Kill Paarthurnax
This quest is given to you if during Season Unending, you talk to Esbern; it will start automatically at the end of the treaty conference anyway, if one is held and you haven't yet spoken to him. Delphine and Esbern have discovered that Paarthurnax is the Master of the Greybeards. Esbern will tell you that Paarthurnax is an ancient enemy of the Blades, and insist that you kill him.
Paarthurnax will be at The Throat of the World. If you talk to him after the conversation with Esbern, he acknowledges that all dragons thirst for power and that the Dragonborn shares this thirst, though he believes that he has overcome this in-built nature through sheer willpower and that he can be trusted.
If you talk to Arngeir and tell him that the Blades want Paarthurnax dead, he will tell you that - although what Esbern said is true - it was because all dragons were in league with Alduin at first, and that Paarthurnax could not help it. He will go on to say that Paarthurnax did eventually rebel against Alduin, and was instrumental in Alduin's first demise. You are given the option to tell him Paarthurnax must die or that you are going to spare him. This will affect the conversation between Esbern and Arngeir if in Season Unending you are forced to negotiate a treaty.
Paarthurnax is an easy foe for those who are leveled sufficiently, comparable to the average Frost dragon. You will receive a Dragon Soul and the usual set of bones and scales upon defeating him.
Killing Paarthurnax will enrage Arngeir who, if you return to High Hrothgar, will angrily lecture you on your decision and even go so far as to threaten violence if you do not leave. After this, the other Greybeards will also fail to acknowledge you. On the other hand, the Blades will talk to you again.
If you let Paarthurnax live, there will be a short scene with him after you have defeated Alduin for good, and he will tell you that he will try to round up the other dragons and bring them into the Way of the Voice, teaching them how to be peaceful. However, this does not make gameplay any different - all other dragons in the game except Odahviing will still be hostile.
If Paarthurnax dies:
- Arngeir retracts the Greybeard's hospitality, and it is no longer possible to ask him for the locations of Word Walls.
- Paarthurnax will no longer be around to provide meditation bonuses to certain Shouts.
- The Blades will welcome you once again, enabling the completion of Delphine's recruitment quest.
- Esbern will offer to take bones and scales in order to create a potion which grants a permanent perk for 25% melee damage reduction from Dragons (currently, however, the potion is bugged and does nothing - see Dragon Research bug section for solution).
- The Greybeards will not host a peace treaty, making the Civil War questline mandatory to complete in order to proceed with the Main Quest (if Season Unending has not been completed and the Civil War questline has not already been completed).
- The quest will never disappear from the journal.
- Arngeir will still disclose the location of Word Walls.
- Paarthurnax will still provide meditation bonuses for Shout words.
- Paarthurnax will appear for an extra cutscene after Alduin's defeat, wherein he details his plans to rein in the Dragons and teach them to live under the Way of the Voice.
- If you have not brought three people to the Blades already, Delphine's recruitment quest will remain uncompleted.
- Esbern will not offer to create the potion.
It is entirely possible to recruit three followers for Delphine and receive the Dragon Infusion potion from Esbern before being given the quest to kill Paarthurnax. The only real consequence of not killing him is no longer having dialogue with both Delphine and Esbern, and thus no longer having the option to go on Dragon Hunts with your recruited Blades. They still, however, act like regular companions. The period in which you need to complete the recruitment and receive the potion is between the quest Alduin's Wall and reading the Elder Scroll step of Alduin's Bane. It is possible to acquire the quest even if you finished the civil war quest-line thus not acquiring the quest Season Unending.
