Originally, Troi was meant to be the outsider character, like Leonard Nimoy's Spock on Star Trek: The Original Series, but her characterization shifted after Marina Sirtis landed the role. She was still half-alien, but she was more sympathetic and emotional than Spock had ever been.Troi intensely experiences the emotions of an alien creature in Star Trek: The Next Generation's first episode, causing her great distress. This would be toned down in later episodes, as Troi can sense others' emotions without being consumed by them. However, while these traits are fascinating, they do not explain her inconsistent accent.
Marina Sirtis Was Asked To Create An Accent For Star Trek: The Next Generaton's Troi
Sirtis Combined Elements Of An Eastern European & Israeli Accent
When creating the character of Deanna Troi, Gene Roddenberry and the Star Trek: The Next Generation team wanted her to appear somewhat alien. This eventually led to her half-Betazoid heritage, which manifested in her dark eyes and empathic abilities. They wanted Troi to sound foreign, but left it up to Marina Sirtis to determine the exact accent. Born to Greek parents in London, Sirtis wanted to develop an accent that would not be associated with any one particular country.
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In a special feature on the TNG season 1 DVD set, Sirits said she incorporated elements of an Eastern European accent and was also inspired by the accent of an Israeli friend. When Majel Barrett appeared on TNG as Deanna's mother, Lwaxana Troi, she spoke with a distinctly American accent. This raised the question of why Deanna would speak with an accent if her Betazoid mother did not. Marina Sirtis later reflected that, if she could go back, she would have stuck with an American accent for Troi.
Troi Gradually Loses Her Accent As Star Trek: The Next Generation Goes On
And She Changes A Lot As A Character
Lwaxana Troi and other Betazoids that appeared on Star Trek: The Next Generation always had American accents, making Deanna's stand out as odd. Because of this, Counselor Troi slowly lost her accent as TNG progressed, and by the end of the show, she sounded American. This change happened so gradually that most viewers probably did not notice the inconsistencies in the way Troi spoke. Troi's accent was not the only aspect of her character that changed over the course of TNG. Her hairstyles and costumes also went through several iterations throughout the show's seven seasons.
Counselor Troi wore civilian clothes for much of TNG, before she finally got to upgrade to a proper Starfleet uniform for the show's final season. Troi had always been a vital part of the Enterprise-D crew, but she was often relegated to storylines involving her love life, many of which stripped her character of agency. Wearing a Starfleet uniform and taking the Bridge Officer's Test made her a stronger character and allowed her to occasionally step in to command the Enterprise-D. Star Trek: The Next Generation's writers did not always know what to do with Deanna Troi, but she eventually became the heart of the show.