User blog comment:OneofthePendragon94/Does someone know what happened to Morgana's mother Vivienne?/@comment-4892425-20130101180129/@comment-5102537-20130101190908

Sounds interesting. However, I don't think they intended to have Uther cheating on Igraine since he started the Great Purge out of grief over her death after all. Moreover, he wasn't with another woman after Igraine's death (for at least 24 years) which actually speaks for itself and proves his love for her. If they had thought it through at all, maybe he had the affair with Vivienne before he married Igraine. Morgana is older than Arthur, maybe two years? That would make two years and nine months having the affair with Vivienne before marrying Igraine. Of course, it's entirely possible that he indeed cheated on Igraine, no idea what the show runners had in mind, in case they had anything in mind at all when creating this story.

In case that Vivienne had magical powers, which is likely, since both Morgause and Morgana had magic, I don't see why Uther shouldn't have known about that. He banned magic after Igraine's death, so it shouldn't have been a problem knowing that Vivienne had magic. He also was friends with Nimueh before Igraine died.

Maybe he killed Vivienne during the Great Purge, maybe not. It would have been very cruel of him to kill the mother of his daughter and I actually don't want to believe it, not to mention that he should actually have known about Morgana's powers since both mother and sister had magic... All very weird.

It's such a shame that they dropped this story completely. To me it seems that they had something in mind but then decided to show the Arthurian legend only. We all know the result of it...