Of course she could have waited until after she had seen .. the poisoning. However, she didn't want to wait that long. She knew that watching it would only make her angrier. Not that she wasn't going to watch it. She simply didn't want to prolong this any longer. When Merlin said that there wasn't more to say, Morgana, for a second, looked as if she was about to argue. But in the last moment she decided against it. Instead she nodded.
She only had one question in that case. "Did you know?" Her tone soft, not at all accusing. "Did you know that Morgause is my sister?"
Morgana doubted that if he did know that he had learned it from Gaius. Not that she blamed Gaius. Not anymore. Someone deserved the blame. But who? She wasn't at all sure. There ... her father. Morgana couldn't blame him and at the same time -- no, she couldn't blame him. She refused to blame her father. She simply wanted to understand why but the only people who had the answers weren't here. Unless ... somehow .. Merlin had discovered. Morgana knew she was wishing fruitlessly. Because if he'd known, he would have told her before, wouldn't he have? Even if he had known and decided not to mention it, her irritation would come and go just as quickly for the opportunity to know why. The stories, the legends about them, were useless. They were contradicting.
They were ... they were hurtful. And seemed to fall in line with the Dragon's words. She knew she said that she wouldn't read them, and truth be told she hadn't read a lot of it still; however, she had needed to know more about her sister. Her only living family. And her curiousity had gotten the better of her after that monstrosity's declaration to Merlin. Better if the witch never knew the true extent of her powers. Merlin had risked so much for her. Morgana might not completely understand why he hadn't told her about his own powers (though she had some clues, after listening to that winged beast) but he still had faith in her. And apparently some how she ruined that. She, unwittingly -- if what Merlin and the previews said were to believed, had made true what the Dragon had said. And even though she hadn't known he'd said it at the time? It only furthered Morgana's irritation with herself.