It it common knowledge that she hatched the dragons in Khal Drogo's funeral pyre? Also, who would consider Khal Drogo's blood "King's Blood"? "Awesome Blood", definitely, but "King's Blood" is rather arguable.When the fuck is Mel going to get a clue? The one thing I find really irritating in multiple POV books is when you know something as the reader that certain characters do not, and they continuously make bad decision after bad decision based on their lack of knowledge. It's fine when I don't know as the reader, we're both surprised together when they learn the truth. It's even fine when you learn about something, right before a character who doesn't does something stupid and finds out the hard way, but it's painful when you know and have known since book 1 and the character continues to do dumb shit for 5 goddamn books based on their lack of knowledge. It's like watching a movie and a character starts to do something and you start screaming at the TV "No! don't go in there! your going to die you idiot what are you doing!?!"
That's how I feel about reading all of the stannis stuff (even though I like him as a character) as he's completely influenced by Melisandre and she's basing everything she tells him on bullshit. I just want to scream at the book "Khal Drogo was the king's blood that was burned to awaken the dragons out of the stone!!!!!!! STFU about it you're 3 years late already!!! How the fuck have you not heard about the god damn dragons! She's conquered half of Essos already surely somebody has told you??? Sailors in every port in Westeros are talking about it! The maesters of the citadel in Old town know! The Iron born know! Hell even motherfucking Samwell Tarly knows about it already! get a clue!"
Really though, with communication being what it is and so much disinformation and confusion in wartime. Eh, I dunno.
Also keep in mind Stannis' wife is sold on Melisandre completely, so she may beat him if he goes against her!