In S05E07 of Game of Thrones Maester Aemon dies. Sam speaks the words for his funeral since it's supposed to be the Maester himself. He says all the usual stuff:
"His name was Aemon Targaryen"
"He came to us from King's Landing"
"Maester, chained and sworn."
But then he said something that struck me.
"He was the blood of the dragon...but now his fire has gone out."
Now I thought that maybe that was just something that Sam added, after all, him and Aemon were close. But of all the reasons that Sam loved Aemon, being a Targaryen wasn't really one of them, in fact they only briefly spoke about it once in the show. So it got me wondering, does he have to say that? Is the Night's Watch somehow obligated to House Targaryen? And if so why? I mean Yorin certainly made it very clear that the Men of the Watch had no obligation to Joffrey!