The Queen of Hearts is the ruler and creator of Wonderland, a spirit-realm dimension of the Monster Girl Encyclopedia world. She was first introduced in the supplementary web information to the cheshire cat profile. A daughter of the Demon Lord and her husband, the Queen is a lilim but also an Alice, having the (positively regarded) succubus mutational trait which induces perma-loli-dom.
As the Demon Lord's third child, this makes her Druella's elder sister. However, in line with her small stature, the Queen is a lot more capricious and childish than her Lescatie-conquering sibling. Within Wonderland, the Queen has created many wholly new species of monster girls purely because their progenitors annoyed her in some way: mad hatters because a matango was too spaced-out to hold a conversation; dormice because a large mouse was too hectic and restless; and jabberwocks because a dragon was acting too uppity at her. Cheshire cats and march hares are also her creations, although those two have the questionable advantage of being created because a werecat and wererabbit managed to please the Queen.
The queen's greatest creations however are likely her personal soldiers, the trumparts. Consisting of human women who gained her favor and were transformed into powerful card-themed monsters, their specific abilities influenced by the nature and potential of the women themselves. Trumparts are able to appear from surfaces adorned with a matching card pattern, and the queen carries a deck of cards with her to summon them at her leisure.
Despite not being the eldest lilim, when it comes to the sheer amount of magic/mana she can exert, the Queen of Hearts is notably regarded as the most powerful of all the lilim.
There is no information on how closely the Queen collaborates with the world-domination plans of her mother and sisters. Possibly she pulls strings from Wonderland like the Fallen God from Pandemonium, or possibly she just keeps to her own little world.