Board Thread:Theories/@comment-27301168-20170507074839/@comment-4663142-20170809091921

Well, I have 2 theories about this

The first one is based on the words of Kruger, you know, the thing with the freedom. Since all Eldians are connected somehow, that could mean that Attack Titan posesses some sort of will to choose it's next owner. Since it never fell in the hands of Marleyans, you could say that the Titan itself can only fall into the hands of somebody who truly cares about the freedom of Eldian people.

Second theory is based on Reiner's remark about Eren mastering hardening in just 2 months. You could argue that it's not really Eren's prowess as a pilot, but the ability of the Titan itself to have a better connection to it's pilot and his desires. So it could be that it's easier to control and learn new moves for the Attack Titan. It would basically make him the "Female Titan #2" though.