Art © Gekkaneko
Sinai, Lady Darkness © sinako777
Benjamina © SpiketheKlown and  sinako777

All of them are wives to the Demon God Skullerack. In  sinako777's world, shadow creatures, demons and pretty much any mystical beings are allowed to have multiple spouses, depending on what he/she wants. Some do (like Skullerack here) and some don't, sticking with one love.

So, what do we got there? Sinai, an angel that Skullerack met and fall in love with. She's his first (and favorite) bride. Lady Darkness, sister of the Horsemen of the Apocalypse and the Mother-Empress of the shadow creatures, thus mother of the current Empress, Alice. And Benjamina, who used to be a mere "Granny Biker" poodle, gained immortality and eternal youth upon marrying the Demon God.

Skullerack sired 5 children with these 3 wives. From oldest to youngest: Sinako and Blitiks (with Sinai), Eris and Victoria (with Lady Darkness) and Clyde (with Benjamina)