The Purple-Dyed Clown Friends

Clown created by Medusa from Black Blood, the Black Clown is able to merge with Crona increasing their respective powers.

Crona is Medusa's child and hope to create a new Kishin, and wields the black blood weapon (usually in sword form) Ragnarok.

Medusa is one of the main villains in Soul Eater. She is a witch who seeks the revival of the Kishin.

Crona's demon sword partner who is basically Crona's blood and is able to shapeshift into many weapons to protect his master.