Fanny Margrethe Kirstine Suenssen was the daughter of a captain, born in Schleswig, and sister of the writers Alfhilda Mechlenburg and Teckla Juel. Left fatherless at an early age and with a delicate constitution, she spent all of her life at home in Copenhagen.
She made her debut with the novel for young ladies Amalie Vardum, 1862, followed by her novel about marriage Tekla Eichel, 1864, examining a conflict-laden relationship on the verge of divorce. In addition, she published two short story collections and the novel Aldrig, 1871, a Bildungsroman centering on a male character. In the 1880s, she wrote newspaper articles on women's issues.