Bosse began her career in a minor company run by her forceful older sister Alma Fahlstrøm in Kristiania (now Oslo, the capital of Norway).

Having secured an engagement at the Royal Dramatic Theatre, the main drama venue of Sweden's capital Stockholm, Bosse caught the attention of Strindberg with her intelligent acting and exotic "oriental" appearance.

[5] Both Bosse parents were now dead, and Harriet, ordered by Alma to leave, used a modest legacy from her father to finance studies in Stockholm, Copenhagen, and Paris.

The Paris stage—at that time in dynamic conflict between traditional and experimental production styles—was inspirational for Bosse and convinced her that the low-key realistic acting style in which she was training herself was the right choice.

She applied for a place at the Royal Dramatic Theatre, the main drama venue of Stockholm, governed by the conservative tastes of King Oscar II and his personal advisors.

[8] Having trained her Swedish to a high level, she was engaged by the Royal Dramatic Theatre in 1899, where the sensation of the day was the innovative play Gustaf Vasa by August Strindberg.

[11] Strindberg, an important influence on the development of modern drama, had become nationally known in the 1870s as an angry young socialist muckraker and had risen to fame with his satire on the Swedish establishment, The Red Room (1879).

[19] Even before their first meeting, Bosse had been inspired by the newness and freshness of Strindberg's pioneering plays; an iconoclast and radical with two turbulent marriages already behind him presented an intriguing and irresistible mix to her.

[20][21] Strindberg was susceptible to strong, independent career women, as well as to dainty, delicate-looking young girls; like his first and second wives—Siri von Essen and Frida Uhl—Bosse combined these qualities.

[24] He immediately picked her out as a suitable actress for the part of The Lady in his coming play To Damascus, and invited her to his bachelor establishment to discuss the role.

[25] Offering her wine, flowers, and beautifully arranged fruit, he shared with her his fascination with alchemy, showing her a golden brown mixture he told her was gold he had made.

Throwing himself into writing plays with central parts he considered suitable for her, he tried to persuade her to act them, and the Royal Dramatic Theatre management to cast her in them.

Bosse asserts in her edition of the Letters that she tended to hang back, as did the management, being in agreement that she lacked the experience for major and complex roles.

[31] In this setting, his taste in interior decoration was revealed to be Oscarian and old-fashioned, with pedestals, aspidistras, and dining-room furniture in hideous imitation of German renaissance, to Bosse's modern judgment.

Bosse wrote in the Letters that she had nothing to do but stay at home and choke down the tears while Strindberg attempted consolation by giving her a Baedeker "to read a trip in".

However, the relationship quickly foundered on jealousy and suspicion, as when Strindberg struck a photographer over the head with his stick, unable to endure any attention to Bosse.

Strindberg would lurch back and forth from adoration of Bosse as the regenerator of his creativity ("lovely, amiable, and kind")[38] to a wild jealousy (calling her "a small, nasty woman", "evil", "stupid", "black", "arrogant", "venomous", and "whore").

[40] During the brief, intense, creative 1901 period, the roles Strindberg wrote as artistic vehicles for Bosse, or that were based on their relationship, reflect this combination of adoration and "suspicion of every word, every act".

Carla Waal counts eight minor and six major roles written for Bosse to act, or as portraits of her, several of them classics of Western theatre history.

The major roles enumerated by Waal are The Lady in To Damascus (1900; mainly already written when Bosse and Strindberg met, but used between them to enhance their intimacy); Eleonora in Easter (1901; modelled on Strindberg's sister Elisabeth, but intended for Bosse to star in); Henriette in Crimes and Crimes (1901); Swan White in Swan White (1901); Christina in Queen Christina (1901); and Indra's daughter in A Dream Play (1902).

He sees the courtiers as representing various stages of Strindberg's own emotions: Tott, in the first glow of love; de la Gardie, betrayed but loyal; Oxenstierna, who has rejected her.

[45] Agnes, played by and representing Bosse, is the daughter of the Vedic god Indra, descending to earth to observe human life and bring its disappointments to the attention of her divine father.

Shut up indoors by a possessive husband, Agnes can not breathe; she despondently watches the servant working to exclude light and air from the house by pasting insulating strips of paper along the windows' edges.

Recognizably, the "insignificant basis of reality" of Agnes' marriage to The Lawyer is the frustration of the newly married Bosse, yearning for fresh air, sunshine, and travel but fobbed off with a Baedeker.

Throughout these shattering events, which left both her children fatherless, Bosse kept up her busy schedule, apart from a few days off, distraught and grief-stricken, after Wingård's suicide.

[56] Retiring from the stage during World War II, Bosse considered moving back to Norway's capital Oslo, the home of her childhood and youth.