When she looked back on it, years and years and years after the fact, when enough time had passed that she could finally divorce the memories from the fear, Toph could admit that at least it gave her one last chance to stretch her bending abilities to their limits after the war with the Fire Nation finally ended.
Running almost as fast as she possibly could while keeping careful track of his pace and exact position so she could make sure that her foot always fell just a moment before his and twisted just so, subtly smoothing the stone to protect him from tripping without wounding his pride. Returning it to its original state, or at least close enough that nobody coming after them would be able to tell the difference, with another small shift when she lifted her foot again. Keeping track of his heart rate, his breathing, every little sign the earth transmitted to her that would warn her if the pace she was driving them forward at was getting to be too strenuous for him. At the same time stretching out her senses as far as they could go to keep track of their pursuers, ready at any instant to open a furrow beneath her feet for them to drop into if it felt like they'd reached a position where they might be seen. All simple enough things on their own, even together for short periods of time, but sustaining that level of focused precision even with her attention split every which way for mile after mile, hour after hour, was not her usual way of doing things and wore on her quickly and made her crave the stone-blunt solutions she usually found to her problems.
The worst thing was that she was in her element. With the rocky foothills all around her just ripe for bending, the mountains beyond them close enough that she could bring them into the fight too, everything in her shouted that she should stand her ground and rain painful rocky fury down on her enemies.
The only problem was that it was their element too. And it didn't really matter that she could out-bend every last one of them; if over twenty people were trying to bring the peak towering above the two of them down on top of them all at once even Toph wasn't cocky enough to gamble both of their lives on her being able to block every last one of them before the stone was destabilized.
Well, maybe if they were just your average earth-bending shlubs. But she was absolutely positive that there was a good mix of former Dai Li agents mixed in with them, and those jokers were actually enough of a threat to make her hold back. Only one of them would have to have more talent or more luck than she remembered to bring the mountain tumbling down over them, she could easily imagine what would happen from there. She might be great at taking on multiple opponents at once, but there reached a point where even her attention would be too split. If most of her focus turned to diverting the rock, even for a split second, the benders behind them would put all their force into sending more down. If she turned her attention to them then gravity would woo the avalanche along, picking up speed and force with every inch it traveled. Even if she could hold her attention perfectly split, every bit of the rockfall that managed to leave the ground as it bumped and bounced its way down the slope would leave her sight as well, and without any practice she didn't know if he'd be able to guide her with his sight well enough to catch every flying bit of rubble before one dashed one of their heads in.
It would be so much easier if she could ask him to make the stand alongside her. She knew that he'd do it, and that they would make an incredible team, and that every one of the jerks chasing them would fall before them. But she couldn't ask that of him. She wouldn't. Because she understood why he'd needed to be rescued in the first place instead of just blasting them all the way to the Foggy Bottom Swamp. She understood why he'd prodded her to flee in the first place instead of letting her crush the whole nasty fort he'd been held in while she still had the element of surprise. It was stupid, and it was frustrating, and it was politics, but she understood. If even the tiniest little lick of flame touched a single one of their filthy hides they'd take it as proof that they were a hundred-percent right in their thoughts about him, and they would wave that proof in the faces of everyone who was in the least bit sympathetic to their cause until they lured them over to their side.
He wouldn't dare allow that to happen, and risk Zuko losing the precious scraps of good-will that he'd painstakingly managed to build up with the other kingdoms of the world in the years since the war had ended.
There was only one choice then.
They ran.