User blog comment:FairyRaven/Fairy Tail Chapter 311: The Country We're In, Review and Commentary/@comment-121.54.8.130-20121207115637/@comment-5268982-20121207120938

I think we sill soon know this, except if Natsu and co. give us the same shocked expressions Jellal did, and discuss over this without giving us a clue about who she is. However, I think she is to blame for Mercurius collapsing and Lucy singing.