Black Ajah speculation swirled all around that, from wondering if Egwene was deliberately given a ter'angreal to disrupt the other one with dangerous results to Sheriam admitting the weave-through-Myrddraals trick works but few know about it. One of my biggest disappointments was expecting genial Sheriam's Black service explained by that, only to have it explained by the fact she wasn't genial at all, but a spiteful child who held grudges for half a century or more. Not to mention being stupid enough to think the Black Ajah was just the White Tower equivalent of HS poseur Goths who had the power to gratify her spite but would let her hover on the outskirts without demanding real obedience.

"We murdered the Amyrlin in her bed and got away with it, but you don't really have to serve the DO or even do anything bad. Now, who did you want publicly shamed and broken again, dear? "

I liked the book a lot, but the healthy blend of startling naivete and lethal cunning we see in Sheriam is a little implausible to me. Anyone that stupid couldn't have gotten as far as Aes Sedai or Black Ajah, and anyone who could rise as high as Sheriam would've known far better what she got into when she swore her oaths. We've seen the whole "I thought I was just indulging naughtiness that was half fake" excuse many times, but it's not credible here.