Taang headcanons(some spicy for when they're older):
When their older Toph realizes she has a praise kink. Mostly because her parents treated her like a fragile doll who can't do anything. So Toph loves being praised for her skills and just in general. Especially by Aang who adores her. That was a fun kink to realize for her.
Aang finds out that he genuinely feels safe arguing and being mad at Toph or with her. Aang constantly feels the need to be the avatar and happy and peaceful all the time. He still has some trauma from when he didn't have control over the avatar state. With Toph he doesn't need to do that with her. He knows she can handle herself, and that it's ok to be angry and stand his ground with her. Also it's just fun to be sassy and argue playfully with her. Heck sometimes it's even fun when they argue seriously about stuff.
Blindfolds for Aang. Whether it's for training or for fun times, Aang genuinely likes being able to see the world how Toph sees it. And training his other senses with her. To the point that not being able to see with Toph around stops making him feel less scared and his heart beat fast in excitement.
They both love nature. Just Toph finding more enjoyment in nature because she constantly was stuck inside as a kid. She can get dirty, climb trees, feel the grass, smell the dirt. And it's all thanks to Aang. Plus with how nomadic and peaceful airbenders our he enjoys her coming to love nature as much as he does.
They definitely get high together. Aang having more knowledge of that than her because again most of her time was spent outside, plus it's hard to try new things when you constantly have to look perfect for your parents in the moring. Aang grew up with monks trying to find enlightenment plus he had friends everywhere. Yeah he definitely knows some things about getting high and weed.
Toph feeding into her parents thinking Aang is the atla equivalent of her motorcycle boyfriend that she ran away with. It just makes her laugh because it's Aang. Plus she wants rebel however she can.
Aang appreciating the little moments where Toph let's him take care of her. Because he knows how hard that is for her. So when she does it, he knows the level of trust she has for him.
Toph constantly makes Aang tons of rock and metal jewelry. Both as a way so she can sense him and keep him safe more. Both also because she's a possessive little gremlin in small ways and she likes to know he loves and wears her gifts. Especially because he's a monk.
They sell jewelry, wooden carvings, vegetables and fruit together that they make themselves to earn money. Not that they really need it but they have tons of extra. I feel like they do that a lot in modern aus too.
Aang learns how to cook, mostly because he's determined to learn to make vegetarian foods that even Sokka will love and eat. But turns out he ends up liking it. A lot. Especially baking. Toph is taste tester. It was really chaotic and disastrous in the beginning. Especially because they both grew up with other people mainly cooking for them. It was another first for the both of them where they're bad at things at first. But eventually got better with practice.
A diplomatic dinners, Toph eats whatever Aang can't eat and is really helpful with his vegetarian food choices. She also gets mad for him when people forget that he is a vegetarian. Because even if Aang where to foce himself to eat meat to be polite. His body is not use to it and it would make him sick.
They are two sassy goofballs and are constantly making each other laugh. Sometimes they have to be sit separately at important meetings for avatar things because one of them would whisper something super funny and cause the bother to laugh out loud. It's even worse if other members of the gaang are sitting with them.
Hand holding and constantly playing with each other's fingers they do a lot. Without even thinking about it. They are constantly about touch with each other. More so Toph.
Toph loves to see Aang be angry and kind of likes to wind him up or hype him up a little. She likes seeing him rant and be a little mean at times. It's fun, but she also thinks it genuinely helps him. Especially when rock bending is involved. Toph believes that breaking stuff genuinely helps with stress more so than bottling it up and exploding it at someone later.
Aang likes putting on Tophs shoes for her for when she has to wear shoes for important events. Cinderella style. Especially when she forgets them. Tophs kind of sensitive and protective about her feet. So it's a show of trust she let's Aang do that.
Aang sometimes bribes Toph with makeouts in closets or bending duels later if she behaves in for important Avatar related things.
Aang visiting Toph when she's giving earth bending lessons to her students. Sometimes with kisses and it makes her students giggle or go ewww. Everytime.
Her parents still don't like Aang, so Toph makes sure they do a lot of pda whenever they visit them to annoy them. Be extra fluffy and cute too. Mainly to piss off her dad. Her mom is slowly coming around to Aang.
Toph introduces the badgermoles to Aang. Yes they're still alive and in the same cave. They definitely like Aang more and are more supportive than her parents.
I feel like when their older they're the type of couple who's arguing if it gets bad it leads to sex or bending duels. Usually the bending duels Toph wins. If it's sex Aang usually wins because it means that he got Toph so out of sorts she just jumps him instead. It means he got her to be emotional instead of standing her ground or be stubborn.
Toph likes laying on Aangs chest and listening to his heart beat. She doesn't need to do that because she can sense his heart always. It's just more comforting to be so close to it and hear it.