Eliann was a Taresian who wished to become the bride of Harry Kim. Harry had been persuaded that he was a long-lost Taresian who had returned home. In reality, he had been infected with Taresian DNA that was slowly transforming him into a Taresian.
Eliann intended to extract Kim's DNA from him, which was how they propagated their species. The procedure would have proven fatal to Kim. He, however, discovered the plot, and he bound and gagged her, then knocked Rinna (another Taresian) unconscious in order to escape to USS Voyager. (VOY: "Favorite Son")
Eliann was played by actress Cari Shayne.
Her name comes from the script.