Crona

As the biological child of the witch Medusa Gorgon, Crona, also known as the Demon Sword, is a demon sword master. They are motivated by their mother's desire to transform them into a Kishin and serve as the meister partner to the true demon sword, Ragnarok. Crona, who is pessimistic and doesn't think highly of oneself, is described as having an "introverted" personality by Franken Stein and his Soul Perception. They are highly pessimistic, anxious, and submissive most of the time as a result of having been reared by Medusa Gorgon, which contributes to their bullying from Ragnarok.

Perhaps Crona's disturbed mental state and propensity for madness make them a frightening foe. This abnormal state of mind results from trauma they endured from people like Ragnarok and Medusa as she tormented and drilled them until learning how to kill, not just from the Black Blood's Madness. As a result, Crona is forced to display signs of lunacy and violence, utter nonsense, and laugh at random times.

A rare blood type created by Medusa that grants Crona unusual talents such as the ability to join with Ragnarok in a way that allows them to acquire power after Ragnarok devours souls and the ability to manipulate their own blood by either liquifying it or hardening it. Crona and Ragnarok are regarded as an advanced type of meister and weapon as a result of their fusion. The wide variety of assaults available in Ragnarok for Crona to select from is one of the benefits of this kind of alliance.

Anime: Soul Eater