So, I had some questions about
@EarthScorpion's homebrew.
Why does your Coadjutor have to be untouchable? His current philosophy is that it is absolutely impossible to kill anyone's Coadjutor no matter what, and trying is horrible because it takes away your nice shiny soul world, all of the characters living in it, and the XP you put into those charms. I mostly don't get why a Coadjutor has to be irreplaceable. There are already charms that let you replace it with your Id or one of your other souls. You obviously need something to regulate your Urge and Torment. The thing is that I don't see why the problem of having a dick of a Coadjutor should never be solved by violence.
It is absolutely in character for a violence focused character who believes himself to have been tricked into being a slave of the Reclamation to try to kill the voice in his head telling him to do stuff. Under ES's rules, this is both possible and verboten. The spirit of the rules says no killing Coadjutors. The letter says that no one from outside of your Empire can enter, and says nothing about your souls killing each other. This is the big thing that I dislike about ES's handling of Coadjutor death. It is unlike Fetich death in that it is philosophically forbidden from happening. Sure, most infernals won't kill their Coadjutors. Sure, having your Coadjutor killed without any way to save it is bad storytelling arguably worse than "Rocks Fall, Everybody Dies." I mostly just feel that the Lord British Postulate exists for a reason, and that I like the way that Exalted as a whole dealt with it: they acknowledged it and included ways for damn near everything to be killed. One of the big complaints about the Deathlords was that they were as completely immortal as the devs could make them.
My other problem is that there is no discussion about what happens after your Coadjutor dies.
Take it as a given that someone will try to kill her Coadjutor at some point, and that they might just succeed. What happens to her Tiger Empire? Does it immediately disappear destroying everything except the artifacts inside, or does it start to slowly unravel from the center out without the keystone holding it in place? Can the Infernal do damage control and possibly learn a new Heretical Charm to make one of her other souls the linchpin of their Empire?
What about the charms she learned to let her Coadjutor speak through her? Can she repurpose those soul-structures to let her Id or one of her kids speak through her?
Does she immediately enter Torment as soon as the stabilizing factor of her Coadjutor is gone? Does one of her other souls take up the burden of directing her transcendental insanity? If so, what does it make her want to do, if it doesn't have a set of marching orders from the Yozis?
These questions and their answers open up a small niche of Infernal characters. They also eliminate the Lord British Problem. By adding consequences to killing your Coadjutor, you make it possible to kill them in an interesting way while also incentivizing players to protect their Coadjutors. Like all backgrounds, the ST should damn well discuss anything that may have an impact on the player's enjoyment with the player first. That's why backgrounds exist. It doesn't mean that it is absolutely impossible for you to lose your awesome ship, just that it would be lost only if the player is OK with it.
By making Coadjutors killable, you also open up your Tiger Empire to trade with the real world. You allow people you like and trust to enter your world. You allow your Coadjutor to be summoned, and interact with its old friends. You allow so many more things to happen.
If there is some other reason to preserve Coadjutors above and beyond Mentors and Allies and the like, please tell me. I'd love to hear it.