Murphy's Lore

The body-stealing aliens from the last book who have been entirely quiet for three years.

More that: Okay, so the ~story~ behind the concept is that Butcher said he could turn any two bad ideas into a good story, and the two ideas he was given were Pokemon and Lost Roman Legion.

Leaving aside entirely that 'the most profitable media franchise to ever exist' and 'a mysterious historical incident involving one of the more culturally relevant historical empires' aren't really bad ideas in any meaningful sense -- he also just straight up doesn't use those two ideas.

For Pokemon, the counterpart here is furies and furycrafting, except they don't really engage with the core idea of Pokemon at all. The basic idea of Pokemon is 'What if there were magical creatures you could catch and fight with and also you could earn the purest love from them.' Furies are ... not that. They are bodiless, personality-less elemental powers. There is frequent mention of people having personal fury partners, many of whom are named, but they are not characters or even pets, they are just sort of set dressing to a magic system that is in almost every meaningful sense just having elemental powers.

For the Lost Roman Legion, the Alerans are meant to be descendants of them, having been isekai'd into another world, except there's nothing particularly Roman about the Alerans. They're just sort of basically generic fantasy Europeans with a few Latin words glued on top. If you took out the Latin, you could say that it was a lost detachment of soldiers serving Charlemagne, or a lost tribe of Celts, and nothing would change.

And it's largely because -- tbh, if you're going to do a 'Sieg is separated from Punish' thing, it makes more sense to have done that when Exdream showed up as part of his definitive, final defeat.

Having his seemingly definitive defeat, but then he shows up again for a cameo, and then shows up again, and then he becomes a villain for like two scenes and is easily beaten twice before he's separated from Punish using a power the protagonist very much did have the first time around but didn't use just feels very weak.

FF6 and FF8 seem like obvious candidates. FF6 is old, beloved, and has a clear dividing point that could make it work very well as a duology. FF8 is a classic, but it's more awkward to divide up in the same way: The obvious way would be to have a first game end with Edea's defeat, but that's like two thirds of the way through the game. Or have it end with the first, failed assassination attempt against Edea. FF4 is plausible too, with the first game ending with the defeat of the fake King of Baron.

FF9 is an obvious one that they'd probably want to do, but it's even more awkward than FF8 narratively, and in terms of just aesthetics it would lose a lot from being translated into the photorealistic style of FF7 Remake.

That said, it seems pretty obvious they're setting up Raito to return as a major character whenever we get the arc where Kaito and Honoka are antagonists and/or allies. Seems pretty likely he'll be the third member of their little team.