I don't like "The Runaway" episode. Imho this is a very strange plot, pulled out of thin air. And most importantly, it ignores Toph's really interesting conflict that could have developed her character.
The episode begins with Toph and Katara fighting over their differences. The most disgusting thing here is not even that their quarrel was taken out of nowhere, but a flashback to previous episodes. The authors based the series on the misunderstandings between Toph and Katara at the beginning of their relationship, completely ignoring their subsequent beautiful friendship. Not only did they throw out Katara's concern for Toph in the desert and their time together in Ba Sing Se, but they also pretended that this particular episode resolved all the misunderstandings, which means it was important. This is ugh.
Do you know what I would do instead of this unnecessary quarrel? I would finally resolve the misunderstanding with Aang that has been going on since the episode “The Desert”.
Remember when Aang blamed Toph for getting Appa stolen? Why not resolve this obvious and hanging misunderstanding? I mean, Aang and Toph don't talk alone at all after that episode, and that's bad.
A dedicated episode about their relationship would have filled that gap nicely and would have also strengthened the characters' bond.
Also, it's in this episode that I would show how Toph learns sandbending. Imagine the conflict that could have arisen: after losing Appa in the desert, Toph realized that she isn't such a great earthbender, because there are things that are beyond her control. She hates feeling inferior, especially when that deficiency caused her to lose a friend.
The sand is too loose, she loses its sight as soon as she lets it go. And the only one she can turn to for help is Aang.
Think about it, why are the dunes in the desert so mobile? What spreads sand and makes it so unstable? The answer is the air. To bend the sand, Toph will have to turn to the opposite element and to the one with whom there was no time to resolve the issue: Aang. And all this is connected not only with her desire to get rid of the imperfections of her bending, but also with the goal of never losing friends again and always being able to help them. And also finally make peace with Aang, her very first friend.
Imagine how Aang would teach her to feel the sand in the air. How, for example, she could see the currents of the wind... How the grains of sand would become her guides into the gaping void above her head that Toph had never seen before.
What wonderful emotions we would witness. The blind girl finally saw what was unattainable even with earthbending. I'm sure it would greatly impact Toph's personality and expand her understanding of things, and I want to experience it with her.
If there is a fanfic about this, I'd like to read it. Because the canon, alas, has lost all possibility of implementing something like this. After all, Toph learned sandbending off-screen, as if there was no emotion associated with it