User blog comment:Stone Roger/Natsu and Zeref have somekind of relation?/@comment-101.161.34.91-20140201135739/@comment-70.26.194.126-20140212040352

Hmm that means Gajeel has something to do with being frozen as well since it was also observed that he couldnt get past the enchantment either. I'm going to take a guess and it has something to do with the dragon slayers or maybe just the first generation dragon slayers.