Crona
Crona (クロナ, Kurona?) is Medusa's child and the wielder of Ragnarok (ラグナロク, Ragunaroku?), a weapon also known as the Demon Sword (魔剣, Maken?), which takes the form of a black longsword. Crona is androgynous in appearance, leaving the character's gender unknown, though Crona is addressed with male pronouns in the Yen Press and Funimation translations of the manga and anime, respectively, for convenience. As a child, Crona's blood was replaced with a sanity-detering substance called "black blood" made from Ragnarok's liquefied body. This forms a symbiotic relationship between Crona and Ragnarok, the latter of whom typically appears from Crona's back in a black, vaguely humanoid form when not in his weapon form. Because of Medusa's abuse and Ragnarok's bullying nature, Crona is extremely reclusive and fearful of almost everything. Unlike normal weapon and meister pairs, who synchronize their soul wavelengths to increase their strength, Crona uses a skill called Scream Resonance (悲鳴共鳴, Himei Kyōmei?) together with Ragnarok, who emits a scream from the mouth on his weapon form's blade that causes it to vibrate and deal additional damage. The black blood can also harden to prevent physical damage, and can extend from Crona's wounds to be used as an additional weapon.
Crona is forced by Medusa to devour human souls through Ragnarok as part of Medusa's experiment to create a kishin. Crona initially becomes Maka's archenemy after infecting Soul with Ragnarok's black blood during their first encounter, but ends up befriending Maka after she purifies Crona's soul, which causes Ragnarok to shrink into a super deformed shape. Following Medusa's defeat, Crona surrenders to DWMA and enrolls as a trial student, becoming closer to Maka and her friends, but is quickly forced by Medusa to act as her spy within the school. Later, Crona is kidnapped by Medusa and brainwashed into forgetting Maka and her friends, once again becoming Medusa's test subject. Crona is eventually ordered to be executed by DWMA for destroying an entire city in Ukraine and killing the death scythe Tsar Pushka stationed there, after which Crona is coerced by Medusa into killing her as part of the final stage in Medusa's experiment. Having fully awakened the black blood, Crona departs to the moon where he absorbs Asura into his body and is confronted by Maka and her friends until Asura resurfaces taking control of the black blood.
In the anime adaptation, after carrying out Medusa's orders to drive Franken Stein insane, Crona tries to run away from DWMA out of guilt, but is stopped by Maka and persuaded into admitting the betrayal.ep. 39 Crona is expelled and imprisoned within the school as punishment but, with Shinigami's blessing, is allowed to help rescue Stein from Medusa, who had formed a truce with DWMA that forbids anyone from the organization to harm her. Crona battles Medusa together with Maka and Marie Mjolnir, the latter of whom also temporarily leaves DWMA to accompany Crona.ep. 42 Crona is mortally wounded while defending Maka in the battle,ep. 45 but is brought back to full health by the rescued Stein and becomes a full-time DWMA student.ep. 51 Crona is voiced by Maaya Sakamoto in the Japanese version of the anime,ep. 7 and by Maxey Whitehead in the English dub.ep. 7
Read more about this topic: List Of Soul Eater Characters, Antagonists