Detail #375: A Weird Pairwise Voice Construction

This post is adapted from a comment I almost made in a facebook conlanging group, but has been reworked a bit. The first half of the idea was just meant to answer a question about marking something else but subject vs. object on the pronouns, but I went whole hog for full NP marking, and ended up taking a twisty turn towards the end:

So, normally, in a nominative-accusative language, the transitive subject and the intransitive subject have the same marking, and the object a different one. In an ergative-absolutive language, the intransitive subject and the object have the same marking and the transitive subject a different marking.

In some split-s languages, viz. the fluid-s* ones, most intransitive verbs can go either which way - either have subjects marked as transitive subjects or as objects. In different fluid-s languages this is used to mark different things, but volitionality seems popular.

However, this only permits the feature to be marked for on intransitive subjects. Workarounds? Well, voices! With the passive voice, you can mark whether the patient volitionally got acted upon, and with the antipassive, you can permit for the subject of a transitive verb to mark whether the action was carried out volitionally or not.

What if you want both? Well, maybe there could be some kind of "split-voiced" verb, where you turn a verb into two, each with an opposite voice, and each intransitive. Maybe using a special conjunction or a special verb controlling them both, or a special form of the main verb with two independent intransitive auxiliaries:

fight-SPECIALFORM Mark-nominative do-3sg Tom-abs do-3sg
Mark (volitionally) fought Tom (against Tom's will)

Maybe the object and subject have different verbs to make it clearer which is which:

fight-SPECIALFORM Mark-nominative do-3sg Tom-abs stand-3sg
Mark (volitionally) fought Tom (against Tom's will)

 Maybe other arguments as well have dedicated verbs? A different solution already hinted at could be this:

verb-splitter Eric-nominative fight-antip. and Samuel-antip. fight-intr
Eric fought Samuel

Now, you may not always have volitionality implying subjectness:

verb-splitter Eric-absolutive kill-intr and Samuel-absolutive kill-pass
Eric reluctantly/accidentally killed Samuel

The verb splitter may be more conjunction like or more verb like or whatever.

*The other kind of split-s language has the verbs being lexically determined as to whether they take the nominative or the absolutive.