Titan eren reason Hanji is obsessed with titans
The reason Hanji is so obsessed with titans is Beacuse when she was a young girl her Mother can back from an expedition and she overheard her mother telling her father about a weird titan that saved her life.
Her father never believed his wife and made her resign from the scouts thinking the stress and fear had made her go mad.
But Hanji heard the awe in her mother's voice and knew she was telling the truth, and from that day she was obsessed with titans doing everything she could to learn about them.
When she was old enough she joined the scouts and every time they left on expedition she kept a eye out for the weird titan her mother had described, 15m tall, long brown hair, perfectly proportioned, muscular, pointed ears, no lips, exposed teeth.
Years pass and Hanji has never seen the titan but she continues studying titans and abnormal titans.
Until one day when the tallest titan ever Recored breaks the wall and titans start devouring everyone until with an earth shattering roar The titan her mother talked about appears and starts killing every titan it sees.
(titan eren)