User blog comment:FairyRaven/Fairy Tail Chapter 300: Where the Dragon's Soul Rests, Review and Commentary/@comment-112.205.106.43-20120924151229

I was thinking that it could Lucy's mom, Layla Heartfilia. Her death seems to be suspicious. Plus, I don't think Mashima will do the time traveling stuff or will he? Plus, she told Lucy about the One Magic before so she could be somehow connected with Zeref? I don't know, just my speculation.