If you don’t kill him, you can meditate on Words of Power with Paarthurnax and get quests from the Greybeards. If you kill him, you can get quests from the Blades. If you don’t kill him, when you defeat Alduin the quest disappears from the quest log. What happens if you don’t want to kill Paarthurnax? Speak with me when the box has been opened, and all shall be revealed.” If you instead choose the second option, Hermaeus will be somewhat angry but he will reply calmly with “Be warned. The abyss will then respond with “Indeed. If you choose to serve the Wretched Abyss, Hermaeus will not be surprised.
