I'm still reading this story — and loving it, by the way — but one thing bugs me. How is Azula still in such good shape after spending a year in a state of catatonia? I'm not sure I would have noticed myself, except that it mentions how fit she is during her escape. Is this explained later?
Speaking as the author, there's a couple ways to look at it- the Doylist perspective is that I'm not a medical expert and screwed up, so feel free to apply MST3K Mantra. From a Watsonian perspective, though, I can give you a couple of convenient Hand Waves- either a bender's muscles don't decay as quickly as a normal person's (Aang was in pretty good shape after his stint as a Human Popsicle, for example, though that could just be general Avatar weirdness) or that one of the spirits (Zhan Zheng, Agni, Roku) with an eye on Azula simply intervened to keep her in relatively good condition.- Master Ghandalf.
Azula wanted us to believe she was comatose for a year, she might be good enough an actor to pull it off – just as planned.
Azula spent the entire year in the Spirit World.
How did Azula generate fire underwater and destroyed her chains?
With sufficient heat and fuel, you can get fire underwater. It's just very, very difficult, for example in real-life magnesium-based fire and acetylene torches are able to burn underwater because they are so hot they actually BREAK water into hydrogen and oxygen which only provides more fuel, essentially if there is just enough heat, then its possible to BURN water . However, since she can already make lighting(which is hotter than the surface of the sun) just by flicking her fingers, that level of heat is already possible...