Paarthurnax (Skyrim)

Paarthurnax (called the Old One by other dragons), is the leader of the Greybeards, brother of Alduin, and son of Akatosh. The player's first meeting with him comes after the Greybeards teach you the Clear Skies shout, which you then use to ascend the mountain up to the Throat of the World. He is not surprised when the Dragonborn is confused over his form as a dragon. When asked why he is a dragon, he replies with "I am as my father Akatosh made me". He teaches the Dragonborn the shout to breath fire and can help the Dragonborn to meditate on his shouts, giving the player an active effect depending on the word chosen.

In the quest "Paarthurnax", the Blades want you to kill him after finding out that he was one of Alduin's allies during the first dragon war. This quest is not essential however and you can still beat the game without completing it.

If he is not killed, Paarthurnax appears to leave the Throat of the World in the Epilogue, intent on bringing the "Way of the Voice" to all Dovah. However, he can still be found perched on the mountain's Word Wall at any given time, and will still aid the player in meditating on Shouts.

Meditation
Paarthurnax will guide the Dragonborn in meditating on words of power. Meditating on a word grants a perk related to that shout until the Dragonborn meditates on a different word. There are three choices:

Fus grants the "Force Without Effort" perk which increases the dragonborn's stagger resistance by 25% and causes the Dragonborn to stagger opponents 25% more. Note that this is for all forms of stagger, not just stagger relating to the Fus shout.

Feim grants the "Ethereal Spirit" perk to the Dragonborn, causing 25% faster health regeneration while ethereal. Note that the effect is only active while ethereal. No constant effect is added to the player's active effects listing.

Yol grants the "Fire Within" perk which increases damage done by flame breath by 25%.

Trivia

 * His name means "Ambition Overlord Cruelty".
 * The invincible Exploit has been patched. He now flies away.
 * Invincible glitch still works half the time with the new patch. He may fly up to the dragon wall and attack you.
 * Paarthurnax is voiced by Charles Marinet (Best known for his work as the voice of Mario).
 * Despite the fact that dragons are immortal, Paarthurnax shows clear signs of great age, including tattered skin on his wings and tail, broken and chipped horns and chin-spikes, dulled color in his skin and eyes and a lot of teeth missing. These could simply be Battle scars. He also has a unique roar.
 * When first speaking to him, the Dragonborn has the option to say "I wasn't expecting you to be a dragon!"
 * After completion of ALL quests and the slaying of all other dragons (except Odahviing), you can speak to Paarthunax atop of the throat of the world and have an option to battle him.

Bugs

 * (Xbox, PC, PS3) When Dragonborn is told by the Blades that Paarthurnax should be slain, the player is sometimes unable to kill Paarthunax. When attempting to kill him, the player will merely see Paarthurnax's health bar gradually decrease to zero at which point it disappears, although during this entire process Paarthurnax seems oblivious. This glitch can be used to the players advantage to level virtually any combat skill by repeatedly attacking Paarthurnax. (You can kill him with cinematic-like melee attacks).
 * During the initial conversation, Paathunax's flying animation can lock up, resulting in a humurous and rapid flailing which ultimately results in his disappearance. Even with Paathunax gone, the conversation proceeds despite the dragon being too far away to hear (speech can be read if subtitles are enabled.)
 * TO FIX: Cancel the conversation by pressing B on your Xbox controller, and Paarthurnax will come back down and sit on the half stone cylinder he was sitting on before. Then initiate the conversation again by pressing A.