Leanan Sídhe - Succubus Bluaz

Leanan sídhe is a succubus from Irish and Scottish mythology and is described more as a muse than a succubus. Her name means, in Gaelic, lover or concubine. Leanan sídhe belongs to the Aos Sí, which is considered to be a supernatural (superior) race, something like fairies or elves.

Leanan sídhe and her victim

This fairy takes human form to find a mortal, human lover. Those who fall into her nets are said to usually have short lives, due to the fact that the demon feeds on their vital energy (somewhat resembling vampires), but their lives are full of fulfillment and achievements. This is because, as mentioned above, this succubus is a kind of muse that inspires artists in particular. In exchange for the muse's inspiration and love, her man must offer her love and eternal faith.
The muse is described as a very beautiful woman, and her victim, if he does not meet his end drained by her, then—in the "best" case—loses his mind.
The legend of this fairy-muse says that she seeks the love of mortals. If the mortal chosen by the fairy refuses her, then she will serve him like a slave. If, however, the mortal falls under her spell and falls in love with her, then he becomes her slave, and his only escape is to find another man to take his place and be drained of strength until he reaches his end.
In folklore, she does not necessarily appear under the name leanan sídhe, and therefore references to her can be harder to find, but you can read about her in the stories of Katherine Briggs, in the legend Oisin in the Land of Youth, or in the poems of Nuala Ní Dhomhnaill.