WOT read through and new questions.

So I finally got done with another full read through of the WOT series. I have been so busy that it took me forever to do so. And once again I LOVED IT. This never gets old no matter how many times I read these novels. I want so badly to help develop the films that Universal plans to make. These characters are a part of me now, ingrained in my head. I connect with two or three new characters every time around. This time around I latched my attentions heavily on Mat and Tuon whereas last time around I was all about Perrin and Faile. I also had more attention for the Black Ajah. Who is Black Ajah that we don't know about yet. I would like to see some opinion on this and also one other thing. I've read a mass amount of theories but I've never seen one about who the third being that is one with Rand is. I have a serious feeling that this is Morridin. If anyone thinks otherwise or knows of other theories on this, let me know.