Board Thread:Theories/@comment-30785465-20170613200126/@comment-28958062-20170614152202

You have seen what happened when Eren drank the Braun magical potion of hardering, maybe that was spinal fluid from a shifter and by digesting it Eren got the hardering ability so I guess they get the key features from other shifters...

I don't what to know what happenes if Eren drinks the Female Titan's spinal fluid but I am sure Jean would tease him to death XD