WARNING: Spoilers for Bridgerton season 1.
Why and when does Simon start wearing vibrant clothing in Bridgerton season 1? The Duke of Hastings mostly dons all black during the first three episodes of the Netflix series, which doesn't go unnoticed by members of high-class society in 1813 London. However, a certain someone inspires Simon to change his drab appearance.
The Bridgerton series premiere establishes Simon (Regé-Jean Page) as somewhat of a bad boy character. He arrives in London just before the death of his father and makes his societal debut with a cocksure attitude that appeals to and repels the very single Daphne Bridgerton (Phoebe Dynevor). But whereas the opening episode ("Diamond of the First Water") frames the Duke of Hastings as a man who's willing to present a faux image, the second episode ("Shock and Delight") provides viewers with the appropriate context of his backstory. As a child, Simon was rejected by his father (Richard Pepple) because of an embarrassing stammer, and because the perceived "imperfection" wouldn't be received well in public. Simon's mother also passed away during childbirth, which made Lord Hastings even more of an unforgiving tyrant; a man who traumatized his innocent son for years to come. When adult Simon arrives in Bridgerton's 1813 London setting, he informs his dying father that the family bloodline - and therefore, title, which his father prized even above his own son - will end with him. Meaning, the new Duke of Hastings refuses to "sire" an heir out of pure spite.
In Bridgerton season 1, Simon's severe style is first acknowledged by Lady Danbury (Adjoa Andoh), the woman who helped him as a child and throughout his formative years. Prior to a social gathering in episode 2, she asks the Duke of Hastings if it would "pain" him to "wear some color," and compares his wardrobe to the "monotonous" London season. Simon cheekily explains that he heard an all-black look was "all the rage," yet flashback sequences from his childhood suggest that he subconsciously wears his (black) heart on his sleeve as an adult. By the fourth episode in Bridgerton season 1, "An Affair of Honor," speckles of gold suddenly appear on Simon's attire, which inspires a long gaze from Daphne at a public sporting event. Soon after, the two share a first kiss. From that point forward in the Netflix series, Simon's style becomes more colorful and bold. Still, he initially plans to leave London because he's simply emotionally unavailable, the result of being raised by a cold-hearted father.
During Daphne's first kiss with Simon in Bridgerton season 1, Simon wears a red coat which thematically aligns with his burning passion. The following morning, he wears the same threads during a duel with his long-time friend, Anthony Bridgerton (Jonathan Bailey), who feels obliged to defend his sister Daphne's honor. By the end of episode 5, "The Duke and I," Simon has now married Daphne, and awkwardly admits that does indeed "burn" for her. The Duke then takes off his multi-colored threads and presents his natural, naked self to his wife.
The second half of Bridgerton season 1 thematically shows that Simon retreats to his old ways. At the family estate, he begins wearing dark clothing again and becomes emotionally distant while Daphne tries to acclimate herself to new surroundings. They couple still has passionate sex, yet the Duke clearly doesn't know how to fully commit, seemingly because he's still unwilling to have children.
By the Bridgerton season 1 finale, "After the Rain," Simon wears black and purple clothing while posing for a portrait with his wife. When the Duke and Duchess move closer to each other, they feel a spark and subsequently reignite their romance. At the season-ending ball, Daphne unloads her true, unfiltered feelings for Simon and pleads with him to forget about his dark past, and to accept that he doesn't need to be perfect. The color motif then comes full circle in Bridgerton season 1, as the Duke approaches his wife wearing an unbuttoned white shirt, which is symbolic of his vulnerability. Simon then disrobes again, just like in episode 5, and offers his natural self to Daphne, this time with an open heart, along with an open mind in regard to the future.