Sort of a side story to "Captured".
*
Somewhere along the line, her crush on Sokka had faded and Katara replaced him as the object of her twelve year old affections.
Toph didn't know how, when or why it happened, just that suddenly she found herself irrationally jealous of Aang (which was the worst part, Aang was such a nice kid if not kinda wimpy and silly, plus he was her friend) and wanting to spend more and more time with Katara (whose motherly instincts were annoying in a different way; stop treating me like your kid and more like a girl).
When Zuko joined them, she just wanted revenge for her feet. But when he started spending all his free time with Aang she was relieved, relieved that it freed Katara up to hang out with her instead.
She knew Katara was somewhat happy about it too. When they were alone together, the waterbender seemed to forget her distrust of Zuko, and she could feel Katara's energy grow sunnier, the way it used to be.
If only I could see her smile. I bet it's the most beautiful smile in the world!
"Katara?"
"Yeah, Toph?"
"When this is over, do you think you and Aang will get married or something? And remember, I can tell if you're lying."
She felt Katara's heartbeat quicken a little and grinned.
"I...I don't know, Toph. We're still so young, after all."
"But if you were older?"
"Honestly?" Katara paused. "I think...knowing how he feels about me, and thinking about all we've been through together and all we've done for each other..."
"Yeah?"
"I think I could picture myself with Aang for the rest of our lives."
Even though she'd expected that kind of answer, Toph's heart sank. This wasn't a little disappointment like when Sokka was busy overprotecting Suki on The Serpent's Pass, this time her heart actually hurt.
"I thought so," she said, then with a forced smile, "You're lucky I can't see or I'd know you were blushing like a maniac whenever you so much as looked at him!"
"Toph, cut it out!" Katara laughed. Toph smiled a little.
"I hope you two are very happy together, then." Because someone like you should always be happy. Always.