User blog comment:Wrath022/Chapter 516: The Truth About Enchantment, Review/@comment-7418318-20161227071721/@comment-30338537-20170102185943

Perhaps the Magical Container(s) will soon be revealed to be a Magical Seed(s) in a normal human. Earthland people sometimes have them growing inside and Edolas people don't have them. Simple explanation of why some people have Magic while others don't and it even matches the recent hype of making things originate from seeds (Dragons, Demons, what's next?)

Perhaps Fairy Heart will be another seed that grows somewhere in Mavis? Will we see an Anksheram seed growing in Zeref and Mavis? Gray just gotta have a Demon seed inside as well.

Why not! Everything originates from seeds these days...