The first reason I thought that anathea could be madame x is because her yveltel holds a soul stone.
As for the 4 lights and darks we know the 4 lights can't be born naturally which means aelita melia are 2 of them then we have ren who is interesting to say the least. he betrayed us but not to be malicious but he is just a normal guy but he has a robot body so ren might be betrayal or he might be a light bc of his robot body