Marianne Dashwood is a central character in Jane Austen's novel, "Sense and Sensibility." She is the second daughter of Mr. and Mrs. Dashwood and is known for her passionate and impulsive nature. Marianne values emotion and romantic ideals, often expressing her feelings openly, which contrasts with her sister, Elinor Dashwood, who embodies reason and restraint. Throughout the story, Marianne experiences the trials of love and heartbreak, particularly in her relationship with John Willoughby. Her journey highlights the tension between romanticism and practicality, ultimately leading her to a more balanced perspective on life and love by the end of the novel.