Aeryn Sun was a Peacekeeper commando, a Prowler pilot who was part of an elite division. She had followed orders completely until she met Crichton. During the events of Premiere, Crais deems her irreversibly contaminated, thanks to the time spent with John as a prisoner. When John makes his escape attempt, she goes with him, and from that moment, she can never rejoin the Peacekeepers. Aboard Moya, she has a huge impact on the crew. The DNA put in her by Namtar during DNA Mad Scientist gives her a close bond to Pilot, and this continues to Talyn, Moya's baby, once it is born. She is like a close aunt to the young ship. She also gains the respect of fellow warrior D'Argo, and the pair fight well together throughout the series. However, the greatest bond she forms is with Crichton, which we first see in The Flax. From then on, she is taken down a path she has never been down before. Love. Watching Crichton get married in I do, I think and then growing old with him in The Locket and several other major events have made their path together very hard, but things seem to end in happiness.

A lot is learned about Aeryn as the series progresses, and admittedly, a lot is quite painful for her. She is forced to confront her past on several occasions, firstly when a recording is discovered aboard Moya, in the episode The Way We Weren't, and also when she goes back to the command carrier at the end of season 3 in Wolf In Sheep's Clothing. She also meets her mother, which sadly ends in disaster, see Relativity or The Choice.

To summarise the key events in Aeryn's journey:

• Irreversibly contaminated, she is forced to leave the Peacekeepers with Crichton and the crew of Moya, where she makes her new home, and proper friends.
• Her curiousity about the "inferior" human, John Crichton is clear, and she begins to develop feelings for the human, which we see in The Flax.
• In The Hidden Memory she takes a degree of revenge over Crais, and cements her position as an ex-Peacekeeper. She still has to relive the past though, in The Way We Weren't.
• She is shot down by Crichton (controlled by the Scorpius chip) and drowns during Die Me Dichotomy. Fortunately, she is saved by Zhaan, who transfers her spiritual energy to the Peacekeeper during Season Of Death.
• She goes aboard Talyn with one of the Crichtons, who she falls in love with completely. She also meets her mother, but Crais is forced to kill her (see Relativity). He betrays her though, and her mother, Xhalax, returns to be killed again in The Choice.
• The death of one Crichton is nearly too much for Aeryn, but she comes through it, and many months later, when there is no difference to the remaining Crichton she falls in love with John again. Despite his initial problems with trust after the amount they have been through, their relationship is cemented when Crichton proposes marriage in Bad Timing.