1. The Knight and the Mage
She has always been her family's greatest hope for advancing their family's position. Female knights are rare, but she fights better than any of her brothers. When a war with the kingdom of Ganikal breaks out, she enlists in the army, and her skill sees to it that she is quickly knighted. Her quick thinking saves the life of a general, and she starts to become a legend. The people wish to see her elevated. The idea that someone can start out as a commoner and rise to true power is appealing in uncertain times.
While the people call out for her to be rewarded, the royal family is less eager to see her married to one of the princes as her father demands. Queens and princesses in the kingdom have little formal authority. The role is mostly symbolic, and they have little power to rule. Instead, they are expected to submit to their husbands. Rather than risk public outcry by denying her altogether, they decide to marry her off to the youngest prince, Prince Thomas, and force him to take his chances with her.
Thomas is the youngest of three princes, and he has a one in one million gift for magic. Some would see his ability as a gift, but his people have always been wary of the dark arts. Thomas has been given a life of isolation, working to aid the kingdom in small ways without recognition. His family sees little risk in marrying the famous knight to someone with little future as a royal.
As the feast begins, bride and groom meet for the first time. Vows are exchanged, but the ceremony is hardly complete before there is an attack, a magical artifact send by an assassin from Ganikal that causes massive devastation. When the smoke clears, all of the royal family is dead except for the new bride and groom.
The two now find themselves in a position of leadership they never expected. They are the only rulers of a crippled kingdom, one that is on the verge of falling to their relentless neighbor.
2. A Bound Guard
The king is dead, assassinated by one of his most trusted guards. The guard, one of the most prominent female knights in the kingdom, has been arrested by Sir Gius, the king's most trusted general. The evidence is overwhelming. She was found with the murder weapon, her family's estate was recently taken by the crown for failing to pay taxes, and a large sum of coins was found in her belongings, payment from an enemy kingdom.
What no one suspects is that she was framed. The true killer is Sir Gius, who is paving the way for a massive invasion by creating as much chaos as possible. He had thought the court would execute the knight at once, removing the last clue that could possibly tie the act to him, but instead, they decided on something else. The knight was taken to the mages, who used a spell called a binding on her. A person who undergoes the binding is incapable of resisting an order from the person they are bound to. Usually it is used on criminals to turn them into guards, but the court is eager to show strength right now, so they bind the criminal to the person she wronged, the young prince who has just taken power. He can use her as a guard, a plaything, or whatever he desires.
For Sir Gius, the decision is a nightmare. The knight is free to protest her innocence, but he comforts himself with the fact that few would believe her. Still, this moves up his timetable. The knight and her prince will both have to be killed before long.
This would be a kind of dom/sub romance between the knight and her prince. The two would eventually start to work together to save the kingdom, but first they would have to find a place of trust, and eventually love.