Board Thread:Questions and Answers/@comment-39463658-20190515010536/@comment-1327106-20190515205232

My guess is that two people cannot hold the power at the same time. Eldia has a very long history and what's more is that the Nine Titans fought with each other, a lot. That's why King Fritz packed up and set off for the island. He was done with this civil war crap that had been going on for hundreds of years.

We don't know how many hundreds of years this Great Titan War was going on, but I find it difficult to believe that in all those years we never accidentally had a scenario where a Pure Titan managed to get some spinal fluid from one of the Nine Titans in its body. We saw how bitey the ones in Trost got with Eren. It seems it would have happened sooner or later in a full-on war.

The fact the power remained consolidated in Nine Titans rather than getting spread around (giving us the Fifteen Titans, or whatever) probably means that it won't work if the previous inheritor does not die in the process of transference.