Cathy, the daughter of Eric and Jane Hayden, was brought up on the land and lived away from home since going to school at the University of New England where she studied Applied Science. She had two brothers, Tom and John. She became the Park Ranger at the National Park and lived with her grandfather, Jack, until his death from emphysema. Matt Tyler eventually came to stay with her (because he had nowhere else to go and because he was good at pleading) -- she had known Matt in their college days and they clashed at times (a lot of times). It looked at first as if they would get together romantically but they just becamse very good friends. She tried to run the farm they had lived on as well do her Park Ranger duties but eventually was forced to sell it off because she couldn't look after it all. She moved to a new place, called Boolaroo ("Place of Many Flies"). Lucy Gardiner and Matt eventually moved in her. Matt was consigned to a "bachelor pad" in the shed, rather than the main house.
Cathy was an idealistic, wholesome girl who felt her work as a Park Ranger was more a vocation than just a job. She quit once because of a clash between her ideals and departmental policy but the call of the Park was too strong and she returned. She was somewhat insecure in her romantic dealings with men and was a terrible cook (though she did try). She loved to ride horses. Her horse Nugget was shot by an angry duck hunter after she cancelled a scheduled duck shoot. She later got a mare named Pippa.
Cathy went to Kakadu to study for a time. Some time after she had returned to Wandin Valley, she got an offer to go to Kakadu permanently to work. At the time, she was developing a relationship with a paleontologist named John Freeman who was helping to escavate some ancient wombat remains in the National Park. He got an offer to go to Darwin and they decided to get married before they went. They were married in the National Park, on Kelly's bluff, with Matt and Lucy as best man and maid of honour and left right away for Kakadu. Cathy eventually sold Boolaroo, forcing Matt and Lucy to move elsewhere.