Detail #255: Inverse Mood (for a few modal auxiliaries)

Let us consider a mood like 'indicative'. For subjects of certain persons, the indicative might be the most common mood, but for others it might be less so – simply put, you don't often need to ask questions about your own doings in the past, whereas you more often might need to ask questions about what the second or third person did in the past. With the second person, it is somewhat common to give commands, but it's less common to command oneself. A lot of similar observations about moods not being equally distributed for each person can probably be made.

While having a full-on inverse mood system might get a tad unwieldy and maybe even unnatural, there could be some default modal implications with regards to person in some circumstances (e.g. maybe certain subordinating conjunctions trigger the modal implication). Let's have "do" be the inverse auxiliary:

I have a thing	(indicative)
you have a thing	(indicative)
... that I have a thing	(indicative)
... that I do have a thing	(optative)
... that you have a thing	(optative/imperative)
... that you do have a thing	(indicative)

Of course, it could also be possible for the verbs themselves to have a lexically determined default mood, or even for verb-person pairs to have lexically determined default moods.

Unlike systems such as inverse alignment or inverse number, this wouldn't thoroughly permeate the system, though, but only appear with certain pairs of moods and maybe, as mentioned previously, in certain limited contexts.

A final potential thing here - maybe do in the imperative would imply non-second person. The reasoning would be that second person is the usual recipient of commands, and so first and third person receiving commands would require the inverse auxiliary. From this, we get the inverse auxiliary also acting as a person marker in certain moods.