My first recommendation is
This is one of my favorite fics of all time. It is crossposted on ff.net. its super long but there is a podfic if it that i will link at the bottom. Also there are notes in every chapter that gives you everything Vathara was looking at to make the chapter.
SUMMARY
"Dragon's fire is not so easily extinguished; when Zuko rediscovers a lost firebending technique, shifting flames can shift the world..."
WORD COUNT
704,200
CHAPTER COUNT
91/91
PODFIC
Ask me any questions you want abt this