Board Thread:Theories/@comment-17499145-20170509021147/@comment-32397552-20170626121921

I came up with the idea that the 9th titan might be the one that Rod Reiss was about to give to Historia back in the cave. If I remember correctly, he said something like: "I choose the most skilled Titan in combat for you" and the label of it was: "the strongest titan". So, if this theory is correct, it means that the power of the 9th Titan is lost cause Historia destroyed the serum by dropping it on the ground.

Plus when Reiner remember his training with Annie and Bertholdt someone said that the cadets were decreased from 7 to 6. This may means that Marley lost the power of the 9th Titan and somehow it went back to the Reiss family again.

It's just a theory, I don't know.