User blog comment:Miskos3/Fairy Tail 521: The Strongest Wizard, Review/@comment-124.104.231.119-20170213101033

Someone from reddit pointed out that Lucy is back to wearing her post 7 year timeskip outfit (the one with my least liked hairstyle). The user mentioned that perhaps Mashima might integrate the scene where Zeref and Lucy meet for the first time then Zeref will make her kneel or something (the one mentioned in the afterword of one of the manga volumes).

I personally think that there is a good chance that it would happen this arc. Though I am not expecting much when it comes to the actual reason of why Lucy would be kneeling before Zeref. Perhaps some hidden connection that would come out of nowhere?