Okay, for the time that i have been spending watching snk, i have been suspecting levi being a sociopath. i say this because he can punch and kick eren without flinching, or showing any hints of empathy for him. he can watch people get eaten alive by titans right in front of him and not move a finger. but, there is always the idea that maybe he had been through watching so many deaths that he just doesnt care anymore. but i think he might be a sociopath because he has the symptoms of it. like i explained earlier, he lacks empathy for eren. but this is just a theory. i don't know for sure.