Toph/ X
In case you didn't get it, this is a surprise shipping. It's my christmas present to everyone! And it says 'X' because In algebra x is the most common letter used as a variable.
After the war, Toph lives in Fire palace, Katara & Aang married, Zuko & Mai married, Sokka & Ty Lee married. All three couples live in the fire Palace as well, all just married. Nope, I'm not making it obvious who's Toph's match! This may be a christmas present, but it's still supposed to be a surprise!
Every day, Toph had to pass by the honeymooner's room, the vibration of a squeaking mattress, giggling teenagers, and felt angry, cheated, and even more depressed than usual, and she didn't know why. It seemed obvious to Iroh, Toph's private counseler, that Toph longed for one of the two married teens. And it seemed equally obvious to him which she was pining for. Toph would reluctantly, and dishonestly agree, knowing all the while that he did not speak the truth.
One day, the two teens were in a state of panic when Toph trudged by.
The one she did not care for ran by screaming in terror.
The other, who caused Toph's face to blush upon exiting the small apartment, came slowly out, seeming ill, walking unsteadily, and collapsed.
Toph barely managed to catch the person, crying out, What's wrong? What happened?
And Mai replied, "I gotta bun in the oven, kiddo."
And try as she might, Toph could not congratulate Mai on her and Zuko's son/daughter - to - be.
She ran from Mai, struggling not to cry.
Kind of short, huh? Poor Toph, her heart is reaching for another's heart that is already stolen.