So this was the first one I wrote, because when fandom gives you both the opportunity to salute two awesome characters and poke fun at a silly adaptation, then you embrace it fullmetallically.
"What happened to your hair?" Mai's voice was flat as she cast an impassive yellow gaze upon the man seated in the floor upon but one square pillow in deference to his old knees, and the little girl standing on the chair behind him. This morning, upon waking, said girl's hair had been secured in a high bun befitting her station and pinned with a three-pointed flame, and the old man had left his thinning gray mane loose to his shoulders, as was typical for him these days. Even when he hosted royal family members, he had never stood much on ceremony. He was prouder of his tea shop than his title, and said that he'd lost too much to make a proper topknot sit in place anymore, anyway.
They had certainly tested the limits of what could be done with Iroh's remaining hair. Even as her mother approached, Izumi added another tiny, slightly uneven braid to the collection trailing down the back of her great-uncle's head, securing it with a bit of thread wrapped several times around the end and triple knotted firmly. Iroh would have better luck with a pair of scissors than picking out the stubby, fraying ends of the seven-year-old's boat knots. Izumi sported a similar head full of chunky black locks, halfway tumbling out of her ponytail and into her face. The girl had inherited her father's sheep-kitten fluff, so Mai could only be thankful that the main gathering had been pulled back with a clasp instead of the tight ebony thread barely visible around the ends. The ones in the very back of Izumi's crown looked smoother as well, as if the girl had either gotten more practice or more help by the time she'd finished the braids in her bangs.
"The princess has been informing me of the newest fashion trends," Iroh explained, holding perfectly still for his would-be stylist until she handed him a half-finished braid to keep in place while she gathered more thread. That embroidery spool looked suspiciously like one of Mai's from her maid's traveling kit. "Apparently Water-Tribe-style braid loopies and ponytails -"
"Wolf-tails, Uncle Iroh!" his great-niece corrected him with a giggle.
"- Wolf-tails have become the latest rage among the young folks, and as a generous connoisseur with a keen eye, Princess Izumi has graciously agreed to assist me in updating my look." Back perfectly straight as he handed the girl the braid end to be tied off, Iroh met Mai's gaze with as earnestly genial an expression as he might have worn in court, no matter the plain and slightly shabby green robes he wore. If she recognized that tea stain on his cuff, he'd had this same set for nearly ten years. "So? How does it look? I know the princess still has a way to go with me, but I think it suits her quite nicely."
Fortunately, her daughter cracked before Mai did, and her husband's uncle was distracted by a fresh round of girlish giggles before the Fire Lady had to decide whether or not to fight the reflexive jump in her cheek muscles. "Did you include your sister in your makeover session?" Best to remain fair and impartial and never, ever tip her hand before she had to strike - or laugh.
Izumi stuck out her lip at the mention of the younger princess. "Honoria didn't want to play." There were a few advantages to having a five-year-old already as self-possessed and aristocratic as Mai herself. At least she wouldn't be stuck with two miniature dandelion heads when the dreads inevitably had to come out. Even if they were cute in ways that Mai would never admit even in the privacy of her own head. "But see, we can pull his braids up and then he can be Uncle Ear-oh!" Gathering the finished product and tucking it behind her great-uncle's ears, Izumi attacked her mother's resolve with a grin entirely too large for her face. Its match only barely fit on the old man. The Fire Lady brought a hand over her mouth in thought, though it did less than she'd hoped to still the muscles around the corners of her eyes. Her girls certainly found new ways to keep Mai from getting bored.
Iroh kept his hair braided for the next two years, never taking out the dreadlocks. When Izumi cut hers in mourning, her hair grew back with a permanent subtle but distinct curl.