She is a side character with pink hair. In the novel, she became a maid. One of the main characters is her brother.
I think the male lead is imprisoned by one of the lead characters. She tried to befriend the male lead of the story.
In one scene, there's a party for one of the lead characters and she and her brother saw each other. I think she was in disguise at the time, but her brother still recognized her.
I also remember a scene where the male lead escaped and tried to abduct her, but the lead characters saw it; I think it happened in the garden of the house of one of the lead characters.
That's all I remember.