Dr. Franken Stein is an eccentric but talented doctor and meister who is known to be the strongest meister to have graduated from Death Weapon Meister Academy and formerly Spirit Albarn's first weapon partner. He later becomes a teacher at the academy upon Death's request and was later assigned to act as a meister to Marie Mjolnir. Being a man of science, Dr. Stein sees everything in the world, including himself, as an experiment. From childhood, he often wanted to dissect the people around him only to be stopped by Spirit. This personality trait made all those around him afraid of him. This strange hobby of wanting to dissect anything he thinks is interesting was still present, even when Stein became an adult. He also exhibits a sadistic and intimidating personality. Stein has dormant madness. He has even admitted that he is especially sensitive to it. Stein ultimately did go insane and struggled to maintain it. He even quit smoking as a way to convince himself. He can't feel deep emotions other than the need to dissect whatever interests or irritates him. This tendency likely seems to be more destructive or psychotic, which explains his dormant madness. He is depicted as morally bankrupt, at least back in his youth. Despite this cruel and twisted personality, Stein does have a kind and compassionate side that worries for his friends and students and he feels the need to protect them. He also exhibits a rather paternal demeanor towards his students.