Those who have read The Wheel of Time books will remember not liking Nynaeve one bit in the beginning. She had a strong personality, much like Egwene, but she seemed extremely unreasonable at all times. While her constant distrust of Aes Sedai and, right then, Moiraine, can be understood, she wasn’t clever with her expression of it, as in, she was blunt and forceful, and that seemed like an impediment to the already strenuous journey that everyone was on. Nynaeve is a lot softer in the series, and we are given a reason for her anger towards the Aes Sedai right away.
Growing up in Two Rivers, she was keenly aware of the terrible reputation of the Aes Sedai and that they would tell lies and were generally up to no good. In addition to that, the woman who had raised her had been treated very poorly by the Aes Sedai. In retrospect, after the events of episode 3, season 2, we wonder whether the Wisdom had simply not passed the tests to be accepted and instead said that it was the Aes Sedai being too snobbish. But she could also have been telling the truth. After all, even Liandrin felt the need to disguise her impoverished upbringing.
Unlike Egwene, Nynaeve wasn’t an adventure seeker. Egwene had left Emond’s Field with the boys and Moiraine because she wanted to see more of the world. Nynaeve had followed them because she was concerned for their safety. The kind of person someone is plays a huge role in the powers they wield as an Aes Sedai, and it is these tiny things about Nynaeve that make her so annoying and also make her so powerful.
Moiriane knew right away that Nynaeve possessed channeling powers, and unlike Egwene, who was eager to be an Aes Sedai, Nynaeve had to be convinced about her abilities. Also, her attraction and relationship with Lan did not just develop because of casual conversations. It happened because he was the first to easily acknowledge and compliment her impeccable tracking powers, and this had been right after they met after fleeing from the Trollocs.
Her ability to track Moiraine had left many people with questions in the series, but it is explained in the books that her father taught her how to detect trails and find people. This is a very important part of Nynaeve’s personality and the reason she started warming up to Lan. Nynaeve had always been powerful, but for many reasons, she had to keep a wrap on it. While in Two Rivers, her age was always in the way of her being taken seriously, and therefore, she was not used to any acceptance or being treated like an equal without a grudging attitude. At a time like that, when a man as powerful as Lan so easily gave her her due credit, she melted.
Another thing we know about Nynaeve is that she is fiercely protective of the people around her. In The Wheel of Time season 1, she could have stayed at Two Rivers and picked up the pieces after her friends left, yet she followed them, wanting to protect the lot. At that time, her powers were very underdeveloped, and she had no idea what they even were. Yet she deemed it fit to try and chase down an Aes Sedai and a Warder, people far more powerful than her, to protect three grown men and a woman. Nynaeve could just never let things go, and it is one of the reasons she had the kind of test that she did with the arches.
While her power first revealed itself in the series because she was trying to keep Lan alive, in the books, it was because of Egwene. When they were kids, Egwene had been on the verge of death due to her illness, and Nynaeve’s furious passion and wish to protect her friend were what gave her power. It was this very frustration and anger that reopened the gates to the high tower for her in the world created by the arches. We don’t think Nynaeve ever wanted great power. She just wanted to live happily with her friends and family. Her power was incidental, and if she was not using it for harmony, she was suspicious of it.
In The Wheel of Time Season 1, Nynaeve had seen for herself the destruction that power was capable of. She knew that unchecked power could have devastating consequences, and the trouble was that she did not trust herself. What Nynaeve knew, everyone knew, but somewhere, the wielder of the power has to trust themselves that they will be capable of the responsibility that comes with it. Egwene had that, and so did Moiraine and the rest of the Aes Sedai. But Nynaeve was still struggling with it. This is why she decided that drinking muddy water was a better alternative than dismantling the block that had formed in her mind. She needed to be pushed, and we may hate Liandrin for whatever reason, but she was the person for the job. She knew what to say and how much of it to say to push a person. It is a given that she was not as sincere as the rest of them, but it was getting the job done, and the Aes Sedai needed Nynaeve to be at her powerful best for the upcoming battle.
When Nynaeve did not initially return from the third arch, Liandrin was conveniently blamed for hastening the process, while it cannot be denied that the others were in on it, too. But they are not the important part. What is important is the lesson that Nynaeve learned when she was there. While she had been able to come out of the first and second archways with only regrets, it was the third one that taught her why she needed to embrace her responsibilities as an Aes Sedai. She could run away right that instant, rejecting everything, and have a simple life like she always wanted. But that would still not mean that her loved ones were safe. As long as the threat of the Dark One loomed over them and Nynaeve refused to embrace her powers, everything she cared for would always be in danger. When she saw that Lan, Mat, and Perrin were killed by the Trollocs, her intense grief brought her power, and the portal opened for her. Nynaeve knew what had happened, and this time, she wouldn’t turn back from her Aes Sedai powers. She had seen why she needed to fight with them and what her importance was. Therefore, we can expect that her mental block will be gone, and she will willingly go to battle against the incoming evil.