Primary

• Sir Zechs Lucifer Older Brother of Rias Gremory
• Sir Zechs Lucifer Husband of Grayfia Lucifuge

Extended

• Rias Gremory Friend of Akeno Himejima
• Rias Gremory In love with Issei Hyoudou
• Rias Gremory Younger Sister of Sir Zechs Lucifer
• Grayfia Lucifuge Sister-in-law of Rias Gremory
• Grayfia Lucifuge Wife of Sir Zechs Lucifer