hot take but the pharim war series by gama ray martinez is actually a pretty accurate portrayal of how splits in systems can work, at least in theory
not of plurality in any way, though the concept of one body ≠ one entity is certainly not new to this world, but the idea of one consciousness slowly or quickly splintering into two, with one that’s basically the same (though not quite) and another that grows into entirely its own thing until they are more than the sum of their parts? yeah
and also the concept of switches, in a way- you don’t have control. headmates, alters, scions- they see things differently, and have different abilities (though not quite to the same level. we’re not superpowered) and you cannot control another headmates actions, nor can you control your scion. you can, however, influence it, sometimes, with effort. there’s also differences in intensity of switches.
additionally, the concept of system responsibility is pretty accurately portrayed by osmund’s banishment. could he control ziary? no. do people expect him to? a little, but not really. does he still have to face the consequences of what ziary did with his body? absolutely. and he does that with grace and dignity.