Nidell was a Halanan female from New Halana and the daughter of a local dignitary on the planet. She was the ninth and last wife of noted Federation terraformer Gideon Seyetik.

Nidell met Gideon during the unveiling of a statue dedicated to his honor after he had finished terraforming New Halana. She was, according to Gideon, infatuated with him from the start. He promised that he would show the galaxy to her which was a very enticing prospect as she had never left her world. She enjoyed her time with Gideon but, like his past wives, she eventually became unsatisfied. However, she would not leave him due to Halanan custom.

Her species had an unusual ability known as psycho-projective telepathy. In 2367, under a moment of great emotional distress on Terosa Prime, Nidell unintentionally created a doppelganger, Fenna, of which she was unaware for years. This nearly killed her and Fenna promised Gideon that it would never happen again.

In 2370, she accompanied Seyetik on the USS Prometheus for his mission to reignite a dead star. She again became distraught and created Fenna, who then fell in love with Benjamin Sisko while docked at Deep Space 9. Gideon welcomed the DS9 crew aboard the Prometheus for a large dinner, for which she prepared the meal, including Gideon's stew recipe. Sisko at first thought she was Fenna, but Nidell told Sisko she had never met him. When Nidell fell ill during the mission, Seyetik later explained his wife's telepathic ability. In order to save Nidell, Seyetik committed suicide subsequently freeing her from the marriage by flying the shuttle, which was prepared for the mission, himself instead of letting it be automated. He was successful, and Nidell recovered. However, she still did not remember her experiences as Fenna much to Ben's disappointment. She returned to DS9, and then New Halana, where she intended to live out the rest of her life after seeing at least some of the "galaxy". (DS9: "Second Sight")

Nidell was played by actress Salli Elise Richardson, just like her alter ego, Fenna.
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