User blog comment:Miskos3/Episode 275: Fairy Tail Zerø: An Eternal Adventure, Review/@comment-5894890-20160312181503/@comment-7418318-20160313075528

Mild spoiler continued I'll still try to keep it vague, but be warned anyway Anime only viewers.

If it is about Lucy, there would be a perfect point to place it.

Imagine seeing Lucy all happy and then when she stands before "the wall" we get an inkling of what she really feels going into flashbacks to show it.

And if it's about Natsu, they could add it in during the journey. When they rest at night Lucy can ask Natsu what he's done all this time and his story is triggering the flashbacks.

The same could be done for pretty much any character they meet, though I think I'd be most interested in Wendy's story over the year.