"The word ‘twincest’ has been thrown around a lot," Madelaine explained. "The way that I rationalised it was that it’s very clear that she grew up in a very, very dark family. The only light that she had was Jason, the only love that she ever felt was Jason. Her parents never really showed her love, they didn’t really care about her, she turned to Jason for everything. The loss of him hurt her so badly, he was her person."
Nothing's stronger than that twin-bond though. But it doesn't cross over to the ~sexual~ side.
"There was no sexual connection," she continued. "It was not romantic, it was that she never felt love from any other person on the planet, so the way she justified that was by making it her person."
Well, that settles it then! Cheryl and Jason are definitely not the new Cersei and Jaime Lannister.