Love
When Taz was very young, she made the horrible mistake of reading one of her mother's cheap romance novels. Needless to say, her innocent young mind was permanently scarred. There were plenty of things in there that a girl her age should never have read.
That became what her idea of romance was. She couldn't understand why so many girls would dream of some guy swooping in, saving the day, and riding off with her in the sunset. Not only was it unrealistic, but it just seemed weak, letting some man save you. It wasn't until she met Up that she discovered that a lot of the things in the book were not true.
In the book, the man and woman knew they loved each other the moment they met. Taz didn't figure it out until a few years after knowing him, and she didn't tell him how she felt until long after.
In the book, the man and woman were completely flawless. Up looked ten years older than actually was, was annoyingly stubborn, had half of his body covered in scars, the other half of him was a robot, and while he was getting better, he was still pretty soft. Taz was short, short tempered, sometimes mean, dressed like a guy, and kept all her emotions besides anger bottled up inside her.
But in real life, their love was so much deeper, so much more pure. It was what kept them alive in battle, and what helped them go on after.
It was so much better than some stupid book.