So I've been obsessively watching, looking up and finding things, and listening to the soundtracks of Merlin recently. I just got past the episode where Gaius gets possessed by a goblin and I got to thinking.
The scene where Morgana goes to get a sleeping draft from Goblin!Gaius, he pretty much just stares into the slowly blackening void of her soul and throws everything he sees and understands right in her face. She of course tries to deny it and loosely threatens him with the whole "I'm the King's ward". But Uther never says anything to Gaius about it meaning Morgana never said anything to him. And it wasn't just because she couldn't tell him without making him suspicious or saying something wrong or whatever. Morgana is very intelligent and practically everything she does is carefully calculated. It would have been like child's play for her to tell Uther and get him to do something to Gaius.
If you watch her face from the beginning of the scene to where she walks out, she comes in with a confident and dignified look. It falters a bit when he starts but comes back when she threatens him. But then when he continues you can see that confidence slowly start to fall into confusion and what I believe is a raw bit of fear. Some of what he says, I don't think she really noticed or understood until then.
At this point I honestly think Morgana could have been saved. That's not to say she would suddenly make amends with Uther, because while I do believe he does care for her and Arthur and tries to do the best for them he is too far embedded and twisted up in his pretenses and lies that there is no making amends with him. But I think she would have learned to trust in Merlin and Guinevere and truly find a caring, protective sibling in Arthur.
I so wish Merlin had trusted her and told her the truth when she was raising an army of the dead. She probably would have been a little angry and hurt knowing he had known and not told her sooner making her feel as alone and unsure as he was. But I think after the initial shock and Merlin explained to her, she would have understood. She had the same natural magic as him and was trying to hide it and survive without Uther finding out and executing her just as he had been. She would have understood his hesitancy in trusting anyone with a secret that big because of her own hesitancy to trust anyone in general.
.....this is what happens when I can't sleep. I get way deep in over-analyzing about my fandoms at 5am