I am most certain when you go to see Paarthurnax for the first time he teaches you only Yol which is just the first word of that power. When he breathes fire revealing yol on the dragon wall go to it and learn it. Right after it says you learned it go into your magick section and spend a dragon soul to learn it yourself. Then Paarthurnax will give to you his knowledge of it. When he did this I found out I was given the second word of that power. So I actually learned 2 words in fire breath before leaving the throat of the world. Interesting.

nobody to comment? Anyone find this to be useful? I would like validation on whether or not you only learn yol when you go to Paarthurnax as I think that is true.

Its likely you learnt the other word from a word wall and he taught you the second word ? Thats what happened to me

EXPLOITTTTTTTT!!!!
Lol jk

He first taught me the second word of the fire shout. I spent no souls to get it.
I already knew the three words he offered to teach after that.

I think all you did was to spend a soul when you did not have to.

He doesn't offer to teach you those shouts, he gives you a perk for one of them. If you meditate on yol, you get 25% more fire damage w/ the fire breath shout, 25% more healing w/ feim and 25% more stagger on foes and less on yourself with fus.

I didn't know Yol before going to Paarthurnax. I learned it from the wall after he blasted it with fire, spent the soul and then learned a whole new word after Yol when he gave me the knowledge of "yol". I didn't waste a soul as normally he only teaches you yol and not the word after it. I was only supposed to learn Yol but because I spent a dragon soul right after reading the wall and right before he tried to teach me I ended up learning the second word upon leaving the mountain.

@omgod did you forget when he asks for you to speak to him as the dovah do? He then breathes fire on the dragon wall which teaches you fire breath and then asks you to use it against him since it had been so long since he had communicated in the way of the Dovah. So yes, he does teach you fire breath.