Detail #363: A (Double-)Quartet of Impossible Cases

These cases probably do not exist in any language

The cases form a two by two system as far as their features go. Consider the result of subject gaps over coordination in languages with syntactic ergativity:

she hit him and ___ ran
run takes an absolutive argument, him is the absolutive of hit, thus it is implicitly him doing the running.

We could overrule this by a case marking either on the "normally ergative" or "normally absolutive" noun - a form of differential case marking. Thus we get two sorts: the puissant ergative  or the compliant absolutive. "Puissant" because it overpowers the absolutive, "compliant" because it cedes to the ergative. Either one should by its existence make the other one superfluous. However, what other uses could they have?

The puissant ergative could maybe appear with causatives? The compliant absolutive could appear with non-volitional intransitives?

I actually see a potentially possible grammaticalization path for the compliant absolutive: a merger with an absolutive pronoun referring to the ergative subject. If the language has a really weird word order, a similar solution for the puissant ergative could be imaginable. The reason I suspect these to be impossible is that they are nouns telling us information about the next clause's verb, and even more so the compliant absolutive is telling us a non-thing: it's telling us which noun isn't the subject, and isn't even necessarily involved.

The next pair of cases would be the analogous forms for nominative-accusative languages: the compliant nominative and the puissant accusative.

These could have similar origins as those in the ergative scenario. However, one might expect these too to have additional uses, such as the compliant nominative maybe always being the subject of passives.

Another thing that often is influenced by alignment is pronoun binding, esp. wrt reflexives and such. We can imagine puissant ergatives and accusatives to control the reflexive pronouns (out of which possessive reflexive pronouns might be the most interesting), or compliant absolutives and nominatives to cede their control of the reflexive pronouns.

Further thoughts in imaginary typology: would there be a (vague) correlation between puissantness and definiteness? How about compliantness and indefiniteness?

EDIT: four additional cases appear if you consider the situation of erg/abs languages with nom/acc syntax (giving compliant ergatives or puissant absolutives), or the case of nom/acc languages with erg/abs syntax (WHICH PROBABLY DON'T EXIST SO DON'T TRY THIS AT HOME FOLKS) (giving  compliant accusatives or puissant nominatives).

A final, late EDIT:
Obviously, these should probably rather be seen as functions of some certain cases than as cases unto themselves, i.e. you'd expect some other  cases to fill these roles. That of course is also sort of up to how they came about - I imagine a compliant nominative could morphologically be the same as the accusative, for instance.