The idea of Phantom Phoenix has re-entered my brain again and despite making zero fucking sense for the plot we're given, I'm almost sad we didn't go in that direction.

For one thing, it would turn his sudden about-face after AJ into actually clever writing. He walks and talks like Phoenix, even throwing in anecdotes related to the events of AJ, but it doesn't feel like he's LIVED those events. You could play on the surface-level dopey characterisation as a sign that something's up with the guy. It would definitely be more compelling than someone we never got to know in the first place.

Second, Edgeworth did tell Phoenix to keep an eye on Simon when they're both allowed to practice law again. Not as directly involved as someone else we know, granted, but with his tendancy to accidentally crack wild cases by running his mouth and consulting strange girls with stranger ideas (not to mention he'd just hired one that's strongly related to the phantom's shenanigans) would make him a powerful threat. This is the same man who briefly altered the legal system to double-dip on dunking a betrayer and poisnoner. He is DANGEROUS.

Hell it might make Phoenix being a playable character worth it. Imagine being in control of someone you don't fully understand until the end, when you realise that not only are they a different person but one that has caused a great amount of suffering for a good chunk of the main cast. You know that "we should make the next lawyer EVIL!" idea that's been floating around in the fandom for AA7? This could be that.

Still drawing a blank on what exactly is happening to Phoenix himself in the meantime... maybe he got caught up with something in Europe and the phantom took the opportunity to take Athena to America under his guise. There's also the fact that Phoenix defends Athena in the last case, which very obviously goes against the phantom's wishes. Frankly I'm kind of mad that he takes the wheel in that case anyway so... have Apollo do it? Really put a magnifying glass on his conflict of interest while Phantom Nick is off ensuring he doesn't get caught.

Not a perfect idea as-written by any stretch but an interesting one to think about.