User blog comment:Ktrfgfg/Chapter 53 and chapter 54 predictions/@comment-13234254-20140107154839/@comment-39.32.162.249-20140107173613

You're right! Maybe Karula is a member of the Reiss family! And when Grisha told Eren that he must rely on "their memories" to understand, he must have meant the whole family's memories (Grisha, Karula and Eren). I guess Grisha just didn't inject titan powers to Eren but... also memories. That seems a bit bizarre 'cause even electricity hasn't been invented in the shown era and they have means to share memories via injections :P