Karen Liu was born to an impoverished noble family from the city of Zemar. Her mother Melanie had served as lady-in-waiting to Queen Laura, but the family had since fallen on hard times. When she was fifteen her father Malcolm was elected councilor, and their fortunes vastly improved.
She met the young crown prince, Richard Stirling, at a meeting her father attended. They fell in love. However, Richard's father, King Aldous, forbade them from marrying, threatening to remove Malcolm from his position as councilor if they continued to pester him. Richard promised Karen that he would marry her as soon as Aldous died and he became king.
Unable to be his wife, she became Richard's mistress, much to the shame of her family, who disowned her. At the age of twenty Karen gave birth to a healthy daughter, whom the couple named Kai.
With the death of Aldous, Karen was stunned to find Richard unwilling to go through with the marriage, claiming he didn't trust her. Since then, she has begun to aggressively campaign for her daughter to be legitimized, which would put her next in line to the throne.
This has drawn criticism. Many believe her real goal is to become queen, with her relationship with Richard serving only as a means to that end. If Kai were named heir and Richard died before Kai was of age, Karen would become regent, ruling through her child.
These concerns have been brought to Richard's attention, and as a result his trust in her has diminished. Lust for power is driving them apart.