Around 1444, Agnes became the mistress of Charles VII, and their relationship quickly became public knowledge. Charles openly acknowledged her as his favorite, which was unusual for the time. This openness made her a trailblazer in the role of royal mistresses, who often remained in the shadows.
Agnes's influence over Charles was significant, and she was said to encourage the king to take a more active role in governance, boosting his confidence and political ambition. Her presence at court also contributed to its cultural and artistic enrichment, as she patronized artists and supported the development of the Renaissance in France.