Eva Stein is the only daughter to Doctor Franken Stein. Being the daughter to the dear Dr. Stein things can get pretty wild around the lab. Eva is always trying to keep her father in check because of his tendency to go mad.
Being the daughter of a man of science, Eva is trying to follow in her father's footsteps to become a scientist (With out all the psychicness that her father has). Eva is a loving daughter and an exhalent Miester. Despite her father's cruel and twisted personality, Eva is the one person that Stain is willing to protect; which might be the reason for Stein's kind and compassionate side.
Eva does have a dormant madness of her own. As she got older her own madness started to surface. When rescuing her father there is a point when she does go insane and struggles to maintain her sanity.
Emotionally, Eva is a loving child and would do anything to protect the people she loves. Although, her father has admitted that he can't understand Spirit's and Maka's father-daughter relationship. This shows he can't feel deep emotions other than the need to dissect whatever interests or irritates him. Stein thinks that he's not a very good father like Spirit is with Maka but despite the family history, Stein could never leave Eva alone.
Eva looks like a mini Stein. An average height with silver-gray heir like her dad and on some occasions wears rounded glasses. Eva has one set of stitches from when her father went mad one day and tried to dissect her on her stomach.
Her soul is a pink featuring the one set of stitches.
Unarmed Close Combat Master: Eva is not only a physically strong fighter but she is also well versed in numerous martial arts techniques; that when combined with her high level of intelligence and adaptability, make for an extremely potent combination, so much so that she was able to help her father effortlessly take down Maka and Black Star while Stein still seated in his chair.
Superior Soul Knowledge: Eva's understanding of soul wavelengths gives her a huge advantage against other users, since she can manipulate her own to match the other's wavelength and thereby nullify or disrupt the soul wavelength of the meister and weapon. This comes from her high spiritual flexibility and accurate observation of her opponent beforehand. She is also capable of greatly modifying her own wavelength so as to make use of any weapon she is paired with. However, her soul wavelength is so high that she does not need a weapon, and can instead channel it through her body and release it as an electricity-like surge.
Weapon proficiency: Despite the fact that Eva commonly uses her masterful hand-to-hand combat skills and her Soul Menace attack, she has displayed incredible proficiency in wielding the weapon forms of whichever Weapon partner she's working with.
At one point Eva does team up with Marie Mjolnir. Marie has a calming and motherly effect to Eva since Eva's mother died when she was a baby. With Marie by her side, Eva makes an attempt to rescue her father from Medusa after the Kishun was set free. Eva also secretly wants her father and Marie to be together.