SPOILERS!!!
Other than Jon Arryn, who probably didn’t know for sure, did anyone know that the Lannister twins were doin’ it before Bran Stark climbed that one tower he really shouldn’t have?
Tyrion, most likely. He doesn’t miss much.
Probably Tywin, too.
I believe Tywin knew that they had experimented when they were younger, because there is a book scene where Cersei remembers when they got caught. But I think he had no idea they were still being stupid enough to continue right under the king’s nose.
Their mother walked in on them when they were kids, but she’s dead by the time of the first book.
IIRC, Aryan let Stannis in on his discovery, which is why he packed up and left King’s landing prior to the events in the first book.
I don’t think Tyrion or Tywin knew. I’m 99% sure Tyrion didn’t know, I think we get some “aha” moments from his POV.
I’d be shocked if Varys didn’t know.
(I’ve read the first four books, but not the fifth, which I’m guessing doesn’t factor in)
Jaime explicitly said (to Cersei, IIRC) that he joined the Kingsguard so that he could be near her and so that they could be together. In response to Jaime taking the white, Tywin pretty much immediately took steps to keep them apart. I figure that Tywin had put two and two together, and assumed that they’d resume hooking up once he could no longer keep them apart in separate cities.
Stannis strongly suspected that his brother had been cuckolded, and in fact was the one who told Jon Arryn in the first place. He thought that telling Robert himself would look too self-serving.
Tyrion definitely knew. He tells Cersei in an early chapter of CoK, before Stannis’ letter gets out.
Littlefinger seems completely unsurprised when Ned tells him, so he likely knew. Varys probably did too. No way the spymaster doesn’t know that. Pycelle knew, because he’s about to tell Tyrion in CoK.
Tough to say whether Tywin knew or not. Tyrion thinks he didn’t. If not, it was a willful blindness to the obvious.
Tywin and Tyrion had to know or at least suspected. The whole reason they were doing it is that the Lannisters had been interbreeding for generations to keep the bloodline pure.
I think that was the Targaryens, no?
Yes, the Targaryens are the interbreeders, not the Lannisters.
No the reason they do it is that they like to fuck each other. They say between themselves that it isn’t an objectively immoral thing to do, since the Targaryans married brother to sister. But the Lannisters definitely condemn incest, as do all of the Westerosians, I think.
I’m pretty sure there was a line in one of the books where Tyrion insinuates that he knew for a while. He says something like “Do you think I was as blind as Father?” and “It seemed unfair that you would spread your legs for one brother and not the other.”
I don’t think Tywin knew as I don’t think he’d have stood for it. When their mother caught them ISTR she specifically said that Tywin was not to be told as she feared what would happen.
Yes, she did. And here’s the quote from A Clash of Kings, the conversation between Cersei and Tyrion:
Ah, I’d forgotten that. I wonder if Tyrion was just making use of what he’d heard from Stannis’s proclamation, or if he’d really known or suspected for much longer than that?