Eren was best described as hardheaded, strong-willed, passionate, and impulsive, which are attributes of both his strong determination to protect mankind and, eventually, his equally strong determination to escape the Walls.
 
Even as a young child, he was so intent on joining the Survey Corps that he argued with and shouted at his mother, referring to the people in the village as "silly" and comparing them to complacent livestock.
 
Eren cared deeply for his friends and family, risking harm and even death in order to protect them. As a child, he took on larger boys who bullied Armin Arlert and, more tragically, he attempted to lift the rubble that crushed his mother during the Titans' assault in Shiganshina.
 
Eren was also capable of displaying violent behavior in defense of people he did not even know. This was highlighted when he attempted to rescue Mikasa Ackerman by brutally slaughtering two of the human traffickers who had captured her.