Board Thread:Skyrim/@comment-12349789-20140528143010/@comment-13518348-20140528170848

Krow Dawnstar wrote: Try going into Dustman's Cairn without the Companions? Most of those caves you can go into without doing the quest it's there for Dustman's Carin is locked until Proving Honor.

I agree, it is unfair that you have to join the Companions in order to get this shout. If you really want 'Fire Breath' you could join the Companions but only progress through Proving Honor.