User blog comment:Omega natsu2/Chapter 369: The Place Prayers Reach, Predictions./@comment-176.240.167.193-20140126173239/@comment-7418318-20140126184155


 * 1) Fairy Tail is renown throughout Fiore and even beyond it's borders and Mirajane is one of the most famous members.
 * 2) Tartarus absorbed some members from regular Dark Guild, each of which probably trembled in fear of the names Titania and Demon Mirajane.
 * 3) Sayla has gotten inside Elfman's head somehow already, possibly granting her access to his memories (unlikely if you aks me, but possible).
 * 4) And this one is the most important: Crawford, the former Magic Council Chairman has joined the ranks, bringing with him vast amounts of knowledge about the magic world in Fiore. And on top of that he can use the magic "Super Archive".

There is absolutely no need for any future versions or conspiracies to explain how Tartarus could know Mirajane's name.