User blog comment:Gourgeist/Shingeki no Kyojin Chapter 66 Review: Wish/@comment-3203692-20150212184159/@comment-26004142-20150212212341

Because the first King Reiss lives on inside of his descendents and dominates them. Recall how Historia claimed that Frieda changed into a different person when she tried to climb over the fence?

It's kind of like in the Dune series and how people with memories of ancestors could get "possessed" by them.

If this is true, then Eren is the perfect vessel for the Coordinate. He should be able to gain access to those abilities without the interference of the memories of the first king.