Izumi Kalan!
Izumi is the oldest daughter (and only daughter!) of Lady Xochi and Firelord Zuko, and the Crown Princess of the Fire Nation. She's their second child and Chun's younger twin sister! Yes, this is my interpretation of Zuko's canon daughter so even though she isn't technically a fankid, I mean... canon Izumi has less than 2 minutes of screentime in TLOK so she may as well be atp JKSKHGJ (real ogs remember when izumi was called honora)
Izumi is the exact opposite of Chun, serious, calm, and logical. Izumi is not exactly a "charmer" like Chun is, she's blunt in her words and prefers not to sugarcoat anything. She is skilled in the use of swords like her brother and they even have matching swords!