Right, like Katara was going to believe that. In the short amount of time she'd seen Zuko and Cordelia interact, even she could tell they had some sort of friendship. She didn't understand it and, frankly, didn't want to understand it. Understanding anything when it came to Zuko only led to her later being made to look like a fool. He may technically be a human being in the technical sense of the word, but she was not going to forget that he didn't have the first clue how to act like one.
"Fine," she stated out loud in a clipped tone, deciding the sooner she agreed and they got this over with, the sooner she could go back to pretending he didn't exist. "I'm ready whenever you are."
If he had told her that she was one of only a handful of people to have ever been kind to him, she might have been a little more understanding. She certainly would have understood why doing the right thing seemed to be such a struggle for him. But he didn't tell her and Katara, who had been raised around love, couldn't fathom any other way to grow up. Therefore she had no real sympathy when it came to him. She may have, once upon a time, but not anymore.