Bertholdt is an Eldian who was part of Marley's Warrior Unit. He originated from the Liberio internment zone and possessed the ability to transform into the Colossal Titan, making him one of the greatest threats to humanity within the walls. In the year 845, he infiltrated Paradis Island alongside Reiner Braun, Annie Leonhart, and Marcel Galliard as part of an operation to reclaim the Founding Titan. Afterwards, he joined and graduated the 104th Cadet Corps who was ranked 3rd in his class and b