Now that he has realized his memories from his past life of Lews Therin, to a certain extent, Rand al'Thor's personality is going to be more erratic and prone to Lanfear's manipulation. One of his defenses against her in her various guises earlier in the series was the fact that he was a different man than Lews Therin was, so she didn't know him as well as she thought she did. Now, since the re-integration, she may be able to play him better than he thinks she could. After all, apparently it took years for him to realize she only wanted him for his power and prestige - not really for love. A case can be made that Lews Therin and Rand are poor judges of character for various reasons - Lews' friends ended up being alienated and becoming his most lethal enemies while Rand pushed all of his friends away because he was scared, while miring himself in negative character traits to "protect" himself and be harder.

Reading WoT critically ends up being a death of a thousand cuts type of affair. At the end of the day, most of the main characters are rather bland, and as others pointed out, the characterization of the Forsaken didn't seem to progress much beyond "power hungry villain with roughly X level of strength in the Power".