She’s a Villain Sue. They do exist. And they share the same traits.
It’s not just recently she started exhibiting these traits. She’s been doing wrong things for years without facing any consequences. Even back in Vanilla, the RAS was doing bad things, and no way could she not be aware of what they were doing. Since it was literally right under her nose.
Sylvanas is more like an anime protagonist/antagonist where everything goes exactly how she plans it and nothing at all gets in her way because everything is perfectly accounted for and she perfectly unlocks powers we’ve never even seen or been hinted to her having before when it’s most convenient for her.
As a person I don’t like Sylvanas and don’t support her actions. But as a character I’m not gonna say she’s badly written just because I don’t like her. She has depth but Sylv haters and Sylv fanboys both fail to talk about it. People who wanna understand her should watch some of the lore videos rather than read these forums.
FTFY. She had depth. She was an interesting character before cata. She lost her main reason for existing with the death of Arthas and instead of her continuing to focus on her people, they turned her into what she hated - Arthas. Especially once she no longer served the Horde.
