Our story begin in a world that, while as technologically advanced of ours, is full of magic and contain being straight from a role playing game or a fantasy novel.
Among the nations of this world, there is one empire which is always governed by a woman. Legends say it is a nation that was founded by a tribe of amazons, and it's why never a man sat on its throne. The other particularity of this empire is that any sapient creature willing to integrate into its society is welcomed into it, whatever their species, but that's a recent development.
The previous empress had a complicated pregnancy, which let her unable to have more kids, and because she had given birth to a son, she decided that it would be his wife who would succeed her on the throne. Since it mean the empress would be the one to choose his future wife, the prince wasn't on board with the idea and, as a young adult, ran away. Long story short, the prince fell in love with a succubus who loved him back, and even married her. But while said succubus, named Loreleď, had revealed her true nature as soon as things became serious between them, her husband had never let her know he was the ‘lost’ prince.
A couple years after said wedding, the imperial guards were finally able to locate the prince, but by then the empress was dying. When she learned her son was already married, and not having the time nor energy to cancel his wedding, let alone organize a new one, the empress decided that whoever was her son's spouse would become heir to the crown, not knowing she would hand it to a demoness.
It was hard for said succubus, to be taken away from her little town and everything she ever knew, forced to learn how to rule a country when all she ever wanted was to live a life as ordinary as succubi can have. But since otherwise the throne would stay empty, with all the consequences that implies, she felt like she couldn't refuse to sit in it.
Then came the time for her coronation, which caused a scandal. First because she refused to hide her true self to her subjects, and few trusted a succubus to have the empire's best interest at heart, but mainly because she refused to change her name as she was crowned as was tradition, becoming Empress Loreleď.
While she stayed in contact with her friends back in the village were she grew up thanks to internet, she couldn't chat with them for long and her position as empress seemed to drive a distance with them. She wanted to visit someday to try to renew her friendship but between her duties and the long preparations needed to ensure she could travel safely, she never found the time until it was too late.
One day demons that refuse to integrate into the empire's society kidnapped all the town's kids, including her friends' son, and killed anyone that had tried to stop them. As soon as she learned of the destruction of her hometown, death of her friends and disappearance off all the town's kids, she took a large potion of her imperial guard with her to investigate. The demons responsible hadn't even tried to be discreet about it so finding there base was fast.
At first Loreleď wanted to observe before rescuing the kids and arresting the kidnappers, but then she saw her friends' son being forced into a ritual to turn him into a demon, and decided to intervene immediately, but it wasn't fast enough and the boy was already in a fully formed cocoon. Since extracting him from the cocoon would kill him, in her rage she killed all the kidnappers.
But while the boy was in the cocoon, the ritual wasn't finished yet, it still needed a drop of blood from a demon to be dropped on the cocoon, changing the kid inside into the biological child of said demon.