Chiana will always be remembered as Farscape's runaway teenager. And that's mainly because she seems to be most of the time. But she has a past and some knowledge that could be of vital importance to the universe.
The Nebari society is very strict, wanting everyone to obey without question. For this they invented mind-cleansing in order to eliminate the thoughts that made people behave otherwise. The Nebari though can fight their own mind-cleansing, so it is only normally used on other lifeforms that take up residence on Nebari planets and as a way to get prisoners of other species to surrender and co-operate.
Chiana was one of the ones who was rebellious. She and her brother Neri managed to escape Nebari Prime though, having been generously given medicals to prepare them for leaving and also a pass to leave the planet. They asked no questions, they simply left without looking back.
It was only later that Chiana and Neri found out the reason why they had been allowed to leave. During their medicals they were contaminated with a time-controlled virus which would make the infected person give their total control to the Nebari at a set time. This did not affect Nebari, but more or less anyone they came into contact with from certain other species. Chiana and Neri managed to find a way to get the virus out of them, so they would stop spreading it. But they had already done some damage, and all the virus would wait for would be the set time. The two also managed to find out that they were not the only carriers the Nebari had sent out, that there were probably thousands or millions more like them.
Eventually the two decided to split up, though Chiana was captured by the Nebari. Her prison transport though collided with Moya, and she eventually managed to win the trust of her crew. This matter was probably helped by the fact that one of the people escorting her was Durka, an old nemesis of Rygel who had been mind-cleansed.
Since then she has grown many friendships, particularly with D'Argo, and the two of them have had serious relationship. However, her rebellious nature got the better of her when she started having a relationship with his son, J'othee, and both relationships were forfeit. She is still seen as a child, particularly to Aeryn, though she has proved herself reliable and trustworthy. However, she is primarily a survivor and constantly thinks of herself before others, something that Rygel admires in her. Indeed, the two are often known to be conspirators. She does have her own soft spots as well though, and for a short while appeared to be falling in love with Crichton.
Even though she tries to hide it, she does care about the crew of Moya a lot and sees them as an extended family. She has tried to hide secrets of her past from them though, such as the reason she was allowed away from Nebari Prime. This started coming back to haunt her when she suspected Neri was dead, but more recently he has sent her a message informing her otherwise. She has seen the crew of Moya as an extended family, and was deeply saddened at Zhaan's death.
More recently though, she has been posessed by an energy rider for a short amount of time, and since started having frequent bouts of deja vu. It's not known yet whether this is a side effect of the posession. She was also present at Talyn's burial, having "mid-wifed" him (can you mid-wife a Leviathan birth?), and is now leaving Moya to join her brother Neri in the Nebari resistance.