Soolin met the survivors of the Liberator on their return from Terminal at the beginning of Season Four. Dorian's companion and lover, she was a skilled gunfighter. She had learnt her trade at a young age after her parents were murdered by hired mercenaries on Gauda Prime. Learning how to be proficient with a gun, she tracked down the killers and avenged her parents' deaths.
After Dorian's death, she initially disappeared in the Xenon base but then reappeared and offered to "sell my skill" to Avon's group. Prone to sarcasm and highly suspicious, she was nevertheless loyal to the Scorpio crew and would occasionally hint at greater depth in her character. She also displayed keen intelligence, figuring out the identity of Cancer in "Assassin", for example.
Soolin was shot down by Federation guards in the series finale. Although the fate of the crew was never officially revealed, Glynis Barber stated in an 2006 interview that she would not have returned for a fifth series, so it is probable that Soolin was killed.
Glynis Barber coincidentally appeared as a mutoid in Season One's "Project Avalon". The two characters were presumably not related.