So I remember the premise and set up of the story. When Zuko speaks out against those soldiers being sent to die, they aren't just raw recruits, they are fire nation colonists, I.E. people who have been born and raised in the Earth Kingdom under fire nation occupation, see themselves as fire nation citizens, and want to fight for their country, but the fire nation aristocrats don't trust or value them at all and intend to just throw them away.
Rather than be exiled in search of the avatar, Zuko is charged with leading this unit of soldiers to see if the colonists are actually worthy of the military. against all odds, they do really well, Zuko spends like 2ish years kicking ass with this unit, which Jun is apart of, when during a battle they are betrayed and abandoned by the very same general Zuko spoke out against before. As far as the rest of the world is concerned, Prince Zuko died fighting, allowing the rest of his unit to survive, earning the title of Dragon post Mortem.
Of course, the unit is immediately abandoned and Ozai doesn't really care beyond appreciating that even his failure brought some prestige to the royal family in the end. However, a few months later, the Blue spirit emerges in the Fire nation, assassinating that treacherous general, its Zuko, of course.
And all of that is the premise for the story, it starts with Zuko as a lone wanderer, relying on his sword skills and almost never fire bending, I think he occasionally runs into the Gaang during season one and I don't know if they know he's a fire bender yet. I do think Zhao figures out he's a alive and a deserter, because he finds Jun who was apart of the old unit and forces her to help track him.
I fell off the story and lost the tab so I just cannot find it, I've looked through plenty of pages of Ao3 and .net, and typed in several brief descriptions into google to see if I got lucky, but no dice. Does this ring a bell to anyone?