This story is a Royal au. The Potter kingdom was not okay. It needed money and the king was nineteen himself. Barely an adult but fortunately he had a sister who wasn't married yet. After the death of Fleamont and Euphemia Potter the Potter kingdom was left with an eight year old king. The black kingdom needed a queen. Sirius who should be the next heir declined to be the king. Wulburga Black was going to die in a month due to some deadly disease and needed a wife for Regulus so he could be the king. Of course he can become a king without a queen but Wulburga Black knew that he wouldn't even marry if she doesn't force her to so the only option was this. Things take a weird turn, secrets are discovered and shit happens. All characters belong to jk rowling but the story is fully mine