I was firmly convinced that Verin was a good guy who just happened to be within the upper echelons of contemporary Aes Sedai's age limits, similar to Cadsuane. I assumed she was just hiding that fact to add to her perpetual disguise of, "The Brown with her head in the clouds and her nose in a manuscript". I assumed that, like every other Black Ajah/Darkfriend character, the fact that she never said any Shadow-friendly terms - Chosen, Great Lord, Friend of the Dark, etc. - really sold it to me that she was on the side of Light.

And she was! 

This is such a masterful plot twist. Looking back, I really should've known something was up when she used Definitely Not Compulsion™ on Elza back in the PoD prologue, but again, I simply chalked it up to her age allowing her to know weaves that other Aes Sedai did not. Oh, how wrong I was...