User blog comment:Morganaforever/Morgana's torturer in 5x08/@comment-5674726-20121117214304/@comment-5674726-20121117220752

''I think so too. To Morgana, Gwen is the only one who she probably did not want to hurt, had she not gotten in her way.''

I'd say that Morgana's animosity towards Guinevere is the result of Uther disowning her.

I believe that at least part of Morgana's motivation, perhaps the chief part, for wanting to be Queen of Camelot is that Uther denied her for Arthur's sake. The idea of claiming the throne doesn't seem to have occurred to her when she was hinting to Uther that she would welcome the news that she was his daughter. Morgause was the one to raise the issue of the succession, and Morgana didn't seem interested when she did. I think that, after her initial attempt on Uther's life failed, she calmed down and decided that it would be a more fitting punishment for Uther if the daughter he refused to acknowledge ended up taking the throne that he intended for his precious son, especially since it would put her in a position to reverse the anti-magic laws.

Then she had her vision of Guinevere being crowned and it was insult added to injury. She's the dirty little secret of the Pendragon family while her servant will be Queen.

Maybe she's come to the conclusion that she shouldn't blame Guinevere for being Queen, and that it's the men of the family who are the problem.