When Winterbourne first meets Daisy, he is impressed by this "pretty American girl" (p.12). However, he frequently wonders throughout the novella whether Daisy is truly innocent or is just a reckless American flirt. He believes that she is "wonderfully pretty" (p27) and that she is totally uncultivated. From Mrs. Costello's point of view, she is "very common" (p.25), so she would not like to meet her: "I must decline the honour of her acquaintance" (p.28). On Winterbourne's proposal for a boat ride in the night to the chateau de Chillon, against her mother's will, Daisy is ready to go with him, even though he is almost a total stranger. We can here say that she is reckless.
In Rome, Daisy walks along the main avenue in the late afternoon, accompanied by Winterbourne and Giovanelli. In Rome, it is considered improper for a woman to be accompanied in public by two men but, once again, Daisy is reckless and stubborn because she refuses to get into Mrs. Walker's carriage to save her reputation: "If this is improper, Mrs. Walker, then I am all improper, and you must give me up." (p.61) She also tells Winterbourne: "The young ladies of this country have a dreadfully poky time of it; I don't see why I should change my habit for them." (p.68). She has decided to be "improper" and to act the way she pleases, even when Winterbourne advises, "You must go by the custom of the place." (p.69). Daisy is, once again, reckless and uncaring of her reputation.
At Mrs. Walker's party, she does not socialize with the other guests but, instead, goes and sits in the adjoining room with Giovanelli for the rest of the evening. The reader wonders why Daisy came to the party if she does not mingle with society. She also calls Winterbourne "too stiff" when he tries to explain the effect of her behaviour on the surrounding people. Daisy "thumbs her nose" at society and its customs, and she even lets people believe she is engaged to Giovanelli when that is not true.
Daisy's final reckless act is when she puts her life in danger, lounging away the evening with Giovanelli in the Colosseum, which was considered a nest of malaria. "I don't care whether I have Roman fever or not". Daisy is aware that going to the Colosseum can be very dangerous for her health but she, as usual, does as she pleases. She justifies her act by saying that she is healthy: "I'm healthy! I was bound to see the Colosseum by moonlight", which is a very inappropriate thing to say in those circumstances. She is determined to go to the Colosseum by moonlight and she does not care what other people tell her. In fact, when Giovanelli admits to Winterbourne that the place is dangerous for Daisy, she is not embarrassed at all (p.84). At this moment, Winterbourne understands that Daisy is reckless and he no longer cares whether "she should be 'talked about' by low-minded menials."(p.86)
Daisy defies people: she does the exact opposite of what people tell her, even if her reputation or life is in danger. I agree with the statement that Daisy was a young woman of the reckless class. After being reckless in her companions, she is indiscreet in her actions which ultimately causes her tragic death.