Originally Posted by
Devvra
What makes Arthas sometimes crazy and obsessed about Sylvanas was, as Kel'Thuzad stated, the fact that she was a mirror image of himself - proud, honorable, person people believe in, person people hope for. She failed in their way, as Rhaegar Targaryen did, as the honorable always fails. She gave this cruel lesson to Night Elves, because she is trapped in her past and everytime someone is reminding her of her old life is making a point that makes Sylvanas suffer.
But Delaryn wasn't Anduin. Why?
Anduin isn't a golden boy, although his role is seemingly important to be a mirror image. Delaryn was reminding her of her previous life, but in Anduin she sees herself from old, the Ranger General who didn't have a choice. She starts to see herself as Arthas (at last!) and she isn't really fond of it. Anduin was her true rival, yet the rival she was so similar to her that she couldn't resist but to comply with him, even unwillingly.
Anduin is looking in her eyes, not begging, not taunting, but clearly speaking words she could speak too in his place if she was still alive. She's not. She crossed the point of no return. She won't be Ranger General anymore. She won't be a hero. She won't be redeemed.
But she can do a two steps back and help him, sealing her fate. That won't make her person everyone loves, it still makes her villain, but a tragic one, one that couldn't let go of the past, even trying so hard, but the past is looking in her eyes.
Sorry, I am a literature teacher, I have something with these analysis. You're free to disagree though!