User blog comment:Alekos23/Fairy Tail popularity poll results on the 19th/@comment-4449950-20140716073721/@comment-4449950-20140716080034

Apparently she's been very popular in Japan since her introduction. Not sure, but I guess people just think she's adorable, kinda mysterious or that she's interesting due to her seeming connections to Zeref etc. Iirc, she got in the top 10 of a poll in Japan some time ago and Mashima was a bit surprised because at the time she was relatively new.