An excellent pianist, Leenhoff was initially hired in 1851 by Manet's father Auguste, as a piano teacher for Édouard and his brothers. Auguste was a domineering figure in Édouard's life, insisting that his son study law and avoid the arts. In their early twenties, Suzanne and Édouard developed a personal relationship and were romantically involved for some ten years. After Édouard left his parents' home, he and Suzanne lived together, although they kept their relationship discreet and secret, especially from Édouard's father. (Leenhoff may also have been Auguste's mistress.) Leenhoff gave birth out of wedlock to a son, Léon-Edouard Koëlla, on January 29, 1852. The birth certificate gave Leenhoff as the mother but "Koëlla" as the father, an individual never identified and likely invented. Léon was baptised in 1855, and became known as Suzanne's young brother. Suzanne and Édouard were finally married in October 1863, a year after the death of Édouard's father. Édouard never publicly confirmed Léon as his son.
Léon posed often for Édouard Manet. Most famously, he is the subject of the Boy Carrying a Sword of 1861 (Metropolitan Museum of Art, New York). He also appears as the boy carrying a tray in the background of The Balcony.
Édouard Manet and Edgar Degas met by chance at the Louvre in 1862, and after an intense conversation and Manet's demonstration on the art of etching, they became lifelong friends. Sometime in 1868 Degas painted a portrait of Manet and his wife. Manet is reclining on a couch and Suzanne appears to be seated at a piano. The mystery that surrounds the portrait by Degas is the fact that the painting has been slashed from top to bottom and right through the likeness of Suzanne. The supposition is that Manet, for an unknown reason, cut the painting. Manet might have slashed the painting because he didn't like the way Suzanne was painted, or because he was feuding at the time with Degas, or he might have been angry with his wife. When Degas saw what had been done to his painting he demanded its return, and he took it back. Degas intended to re-paint the likeness of Suzanne at the piano and he reiterated his intention to Ambroise Vollard in conversation with him around the turn of the century. Degas never got around to fixing the painting and it remains in its slashed state in the Kitakyushu Municipal Museum of Art in Japan.
Édouard Manet, The Reading, 1868
Édouard Manet, Mme. Manet in The Greenhouse, 1879
Édouard Manet, Mme. Manet, On A Blue Sofa, c. 1880