Aligura

Aligura (アリギュラ, Arigyura), the 'Queen of Monomania' (偏執王, Henshū-ō) is one of the Thirteen Kings.

Appearance
She wears a metallic mask over her eyes that looks similar to Femt's except hers can open in the middle to reveal a single Cyclopean eye.

Plot
Before the series began she was dating Deldro and she genuinely loves her boyfriend and her affections were reciprocated. What wasn't reciprocated was her desire to turn him into a blood monster that could possess a body that was more attractive which she did as she literally liquefied Deldro body, empty Dog Hummer of his blood and replaced his blood with the now liquefied Deldro.