User blog comment:BlackWizardZeref/Fairy Tail Zero Chapter 10: Law Review/@comment-4933386-20150417041757/@comment-24039250-20150421010307

Law (Fairy Law/Grimore Law) is a neutral spell. It can be black or white, as one can see from Fairy Law and Grimore Law. Law I feel is a type of Magic that reflects the person that is using it. Remember it kills those who are seen as enemies to the persons heart, so a "black" heart see those of "white" as enemies and vise versa.

As for the Zeria I agree, either she isn't real all together, she dies before Fairy Tail is formed, or she is the one taking the picture of the others and goes to travel the world.