Contessa, the Vampire Lilim

Being a daughter of the Demon Lord, Contessa was a Lilim. She was also a Vampire monster. Unlike other Vampires, who looked down upon all humans, she only wasn't really fond of men, but loved teasing women. Contessa was extremely powerful with magic, certainly because she had both monsters Demonic Energy.
She never really looked for a husband, however, by her mother's order, she was **** to. Still, she didn't want to do it. Her sister, the Queen of Hearts, suggested that if she didn't want to seek a man herself, she could order someone to find one for her. Contessa thought this was an interesting idea and started to work on it.

After some time, she decided to create the Black Knight Monster Girl. However, she built multiple specific rules for it. All for her own sake, as she wanted a husband absolutely worthy of her. And also because it'll make things rather difficult, thus increasing the time she would stay single.
The first rule stated that for a girl to be a Black Knight candidate she would need to be of pure heroic blood, meaning born to be a hero.
The second stated that the girl would need to be in love.
The third stated that the man she loved would need to love Monster Girls.
These were the simple rules for a woman to be Contessa's Black Knight candidate, yet very hard to accomplish. Most of her sisters claimed that these were impossible rules, used to fool mother, but the Demon Lord said that as long as Contessa is happy with the result, there's no problem. She also believed that soon enough, someone like this will appear.

Anna was born to be a hero. However, she didn't know it. And the Valkyries from the Heaven Realm, an alternate dimension, couldn't detect her heroic blood. When Smith started to study the Monster Girl Encyclopedia, he became more and more attracted to them, slowly falling in love. Anna loved Smith, making her the perfect Black Knight candidate.
She lived in the Guybou Nation, a country next to the Royal Demon Realm, homeland of the monsters capital, the Demon Lord Castle. Using extremely high magical spells, Contessa knew Anna was a hero, so she kept an eye on her. When she felt the growth of Smith's love for Monster Girls, she tried to cover that fact, but her mother already knew it. In fact, it was the Demon Lord who put an undetectable magical veil around Anna, hiding her from the Valkyries.

Now that Contessa has her Black Knight candidate, she had **** but to tell her family the other rules. In order to become a full Black Knight, Anna would need to go on a quest.
Smith would be the knight's squire. She would need to make four Monster Girls become the wives of her squire, proving their deep love for him. The monster are, an Elemental girl for Anna's sword, a Wolf family beastman to keep track of her squire, a Centaur family beastman to be her steed. She would then have to sexually subdue a monster of the Dragon family.
In addition, to make sure Anna has all of them under her control, the Monster Girls would need to show submission to her squire, by taking his dick deep inside them. As a proof, while cumming in or on the monster girl, a pink magic rune with the monster's symbol would appear in his penis, trapping their Demonic Energy in it.
Moreover, Anna has to conquer the wives in a certain order. She can know it by having her lover shower her breasts with his jizz, thus making the symbol of the monster she has to acquire appears.

The Demon Lord thought that these were too much rules, and too much work for the girl. She would accept her daughter rules only if she made things easier for the candidate. The mother suggested that Anna could freely chose the first monster wife, and that she could have absolute authority over two Monster Girls. Contessa protested but finally agreed.

Contessa decided to begin Anna's monsterization at the Respari Forest, planning to meet her again later.