Tokka alternate universe where Toph hasn't learned metal bending and the 100 year war is over. They are both around the age of 16, I know chronologically it doesn't make sense, but uh, well I'm the author so, I have the power.
Walls of Metal, Hearts of Steel
The mission was to get in, grab the files that were crucial to finding out where the outposts of the rebellion were and where their supplies were, assisted by a small group of earth bending soldiers, Toph and Sokka were to carry this out. Prior to the mission, Toph and Sokka had some occasional flirting once in a while, a stray rock that bumped Sokka on the rear when they're walking, or those ever so subtle moments where Sokka would "accidentally" fall on Toph. Other than that, they were just friends.
Toph and Sokka laid on their bellies looking over the camp where they were soon to attack. Sokka scanned everything and wrote every position of every guard, not only did they have a mass of tents, they also had a prison cell holding three or four, but it was hard to tell because there were two separate boxes, each made out of solid steel. Sokka thought of the steel on the boxes as he felt the steel resting on his back, if it wasn't in its sheath, it would have sliced through his skin as he felt it. He looked over at Toph whose head was not faced toward the camp but toward him. It quickly flicked back to look over the camp, Sokka knew she was still "looking" at him, with her earth bending, and it made him blush. This was the third night, they'd spent on this ridge, watching, waiting, observing. "We strike tonight" Sokka uttered in a low voice, "let's return to camp and then strike." Toph and Sokka crawled back out of sight and got up and jogged back to camp. Sokka was a ways ahead of Toph when she yelled forward, "you have a giant stride!" Sokka hadn't noticed the distance, but Toph obviously had, he slowed his pace to meet with Toph's pace. They returned to camp and began to go over the game plan one more time. The plan was to have Sokka and Toph come from the front and draw enough attention for the others to free the prisoners and grab the intel, Sokka's term for the intelligence, the other soliders liked it but Toph didn't. Most of the guards were stationed out front, so it wouldn't be too hard to carry out the plan.
An hour later, they were all in position, the moon was half and was high in the sky, but there was 2 campfires in the camp, lighting the entire camp, one toward the right, one on the left. Toph and Sokka attacked, sprinting forward, Sokka's sword was unsheathed and thirsty for blood, Toph's fists were covered in large chuncks of rock. 3 guards spotted them and went for a counter attack, one shot a constant stream of fire toward Sokka, a rock wall shot up as Toph made some large body movements, they huddled behind it. One hundred meters in front of them water was dumped on camp fire number 1, then number 2. It became much darker, only the moon lit the camp. Then another stream of fire shot out of the guard's fist. Lighting up the dark, Toph forced the wall forward and it crushed the guard against the ground, the only thing above ground was his helmet, with his head still in it, his body was forced underground, Sokka charged toward a guard on the left and pierced his sword through his heart, he screamed as blood spurted out of his back where the sword exited his body. He fell to the ground, to his right, another one fell, half of his face covered with gravel and red paste. Toph and Sokka penetrated the camp forward, pushing hard, looking to each other for support, when they needed it. Apparently, the "intel" was farther back then they'd thought, so when Toph and Sokka approached the metal boxes, they decided they'd open them. Toph found the nearest rebel with a jingling sound on his belt and yanked off the key and gave it to Sokka, he put it in the lock, unlocked it, and went to get the other one. They opened them at the same time, they were both met by a crooked smile.
A man waited in Sokka's box and a woman in Toph's, unfortunately, they both had a foot in their box and did not expect a jolt of electricity to travel into them from the box, they had just shot them with lightning, Toph collapsed to the floor and began seizing, Sokka did just about the same, and when they awoke, all they saw was the inside of those black boxes. Sokka thought the worst as a beam of light shone through the small slit in the top of the box, it was morning. The door opens, "time for your punishment."
Toph awoke furious, she threw herself against the wall again and again and again, trying to reach what she wanted on the other side, and it wasn't freedom, it was Sokka. "SOKKA!" She screamed, his voice did not greet her but that only fueled her fury. She slammed her shoulder into the wall that she thought she shared with Sokka, she slammed over and over and over. She finally calmed herself, and took a steady stance digging her feet into the metal beneath her, finally, she reached out and punched with all her might, the metal did not budge. She screamed, the pounding in her fist did not match the pounding she felt in her chest, yearning for Sokka's touch or his voice. She backed up against the other wall, the box was about 10 meters on each side, she put one foot on the wall, and one on the ground, and launched herself toward the other wall, her shoulder banged into the wall, it shuddered and creaked as she sailed through the wall. She landed on her side in Sokka's cell, and she felt around, she may've pierced metal, but she couldn't see through it like earth. She got on all fours, searching for Sokka, She was so happy just to be with him again, she crawled around the box and finally got to the last unchecked corner, she felt his foot. "Sokka?!" she exclaimed, he did not say anything, he did not move, her heart raced but thought he was just unconscious, "Sokka?" she repeated. Her hand moved to her chest, she felt nothing, no beating, no warmth, no Sokka.