Yeah it completely avoids the problems with a Zuko SI, being that the existing dynamic is... vaguely defined. We don't know how often he would meet with his father or sister, but a first born of the third sibling would be someone that is well take care of but not often included in much until he shows potential of Iroh latches onto him emotionally. Gives wiggle room to set the narrative comparatively.
I'll be going with this most likely.
I'm still unsure about the whole Ninjutsu or Gamer aspect though. They both allow for illusions, in theory, which is important.
In complete and absolute seriousness. I'd ask yourself seriously if they really contribute and if there isn't a better way existing
in universe to accomplish what you're want.
If you just want an illusionary element, might I make a suggestion?
Spirits
exist in Avatar and are supremely under utilized and, IIRC, after Lu Ten died I believe Iroh went on a bit of a lark that involved meeting them? I may be confused. Regardless, they often have illusionary powers. Build up to it over the course of a fic.
Consider starting it out with a trick of fire bending, causing smoke and heat haze to cause confusion and the like, and have it build into proper illusions possibly via learning from a spirit at some point along the way. In the hypothetical scenario of "a third son of Azulon is your dad and died" maybe you could have him have had a thing about learning about the Spirits and the Spirit world because as a third son nobody cared if he just fucked around with that kind of thing since his father had an heir and a spare already. Which would give you a start on that.
Firebending is stupidly versatile anyway, arguably the most so of any form of bending because of all the stupid bullshit one can do with "I can create my element wherever and also dude I demonstrably can manipulate fucking heat by exciting the fuck out of atoms with kung-fu" as see with things like combustion man and lightning bending. Theoretically fire bending could mimic any other form of bending, you could fake being the fucking avatar in theory. Not that I'd suggest it for this fic.
Because I'll be entirely honest I can't say that, in this case, Ninjutsu or Gamer powers actually add anything. you already have A. An
extremely strong selling point in the form of an ATLA SI fic which is actually quite rare with the obvious reader bait of Azula's team, and B. are already kind of lining up the metaphorical unicorns in your garden to an extent with the initial premise. Anything more will kind of just be messy, in my opinion.
