When you first meat Paarthurnax, one of the first things he does is tell you to use the Fire Breath shout on him as a proper dragon greeting. Very obscure one this is, but in the book King Edward (which only appeared in Daggerfall), near the end is:
"Ma-Tylda!" Akatosh exclaimed, "She deigns to bestow her presence on us!" His wings lifted and unfurled, and the Companions broke and ran for cover as he took flight. The two dragons wheeled through the sky, spouting great gouts of flame against the purpling sky.
"They're fighting," Edward cried, "what does it mean. Who is Ma-Tylda?"
"I don't know who she is, son," Moraelyn replied, "but they do not fight. You behold a dragon greeting ceremony." The pair alit beyond a rock outcropping out of sight.
An extra-interesting bit is that the book was never meant to be taken as "canon" lore, as it's a fictional story even to the game world, yet they still thought to include it. Either that or it's an extreme coincidence, but that's no fun.