Catherine was a troubled child, she could not be tamed and her wild personality that strayed her from the conventional lifestyle was there from the start. She constantly tested the trangression boundaries and her father recognised this.
"Why cant you always be a good lass Cathy?"
"The greatest punishment we could give her was to keep her away from Heathcliff."
Catherine was always at her happiest when she was up playing on the moors, usually with Heathcliff. During the novel she explains to Nelly a dream she has that stops her from being happy in heaven and being thrown back onto the moors at Wuthering Heights where she is at her happiest.
"the angels were so angry that they flung me out into the middle of the heath on the top of Wuthering Heights; where I woke sobbing for joy."
She is even burried on top of the Heights - where she was at her happiest.
Catherines love triangle between Edgar Linton and Heathcliff is the main romance within the novel, when she decides to marry Edgar it is because of the social security that she wants her future children to have and not because of the love she feels for him.
"It would degrade me to marry Heathcliff." - she cannot marry him because of his social status and that they would both be "beggers"
"My love for Linton is like the folige in the woods it will change over time." - Her love for Heathcliff is strong and will never change but she cannot feel the same for Linton
"You have both broke my heart and killed me." - she claims just before her death that it is Heathcliff and Edgars constant fighting over her that has led to her death