Board Thread:Theories/@comment-32443384-20180201102915/@comment-1327106-20180201170110

SaiyanJack wrote:

Shifter Lineage: to become a shifter a human must be injected with a titans’ spinal fluid and then triggered into transforming by severe injury or by the scream of a titan shifter of royal blood, then the titan form must devour a current titan shifter, the result is that the titan returns to their human form and their titan form is replaced by the new titan shifter form, of which there are nine

Still devouring my morning tea so not going to comment on the theory part, but the quoted part above is not entirely correct.

Zeke's scream method does not rely on Titan spinal fluid. It's his own spinal fluid being used.

Secondly, after injection of Titan spinal fluid, there's no evidence that the soon-to-be Titan needs to be triggered into transforming by injury. Child Eren is not beaten by Grisha after injection, and the worst the Marleyans do is push the Eldians off a ledge when exiling them to Paradis, which doesn't seem to be wait triggers the transformation. There aren't any shots of injured Eldians at the bottom of the sea wall prior to transforming.