I know the fortune teller is a episode a lot of people are indifferent to, but it's always stood out for me because of one reason: Meng.
I LOVE her. She shows up in this one episode, and yet everytime I watch the episode she steals the whole show. Im currently watching someone react to ATLA, and I skipped a lot of early season 1 episodes... but I remembered Meng and watched the fortune teller and yeah, I stand by that choice, I LOVE her. I just find her so charming, you can tell she's trying to be emotionally mature about Aang not liking her & her talk with him shows that, but at the same time she can't help but feel bitter towards Katara—as she calls her floozy out of her ear shot, so she clearly feels bitter. Despite feeling this way, just moments before she was being nice to Katara—telling her to take care—because deep down she knows it's not her fault Aang likes her. She clearly has some insecurities based on how she talks about herself/compares herself to Katara ("and her hair is so manageable") but she's still being nice to Katara and having the emotional maturity to have that heart to heart with Aang/let him go. I know she literally does not show up anywhere else in ATLA, but I am SO attached to her and I want nice things for her.
I don't know, this isn't very structured or anything, my thoughts are pretty scattered, and there's no big point to the post except that I really really like Meng, but yeah! She's underrated. I know people love Song from that one episode where she helps Zuko and Iroh, or Jin who Zuko went on a date with, and like... yeah, I really like them too, but I haven't seen anyone talk about Meng which sucks because I also adore her! I know these are side characters who show up for 1 ep and never show up again but I've always wondered how things worked out for them... Does Song ever learn the dude who stole her ostrichorse was actually a fire prince and is now firelord? Does Jin ever learn she went on a date with the future firelord? What must they think of such things? Or all the people Zuko served tea to, do they ever sit there and think, holy crap, the firelord served me tea? I'm getting a bit off topic but I am SOOO intrigued by the side characters in ATLA.
Anyways yeah those are just some thoughts I've had regarding Meng & the other side characters who never show up again. I always love when a fanfic explores what happens to them, tbh—it's amazing that even with only one episode under most of these characters belt, they manage to be interesting and even complex at times.