Exploring grammatical forms not used much in English is part of the best fun of building languages. Here’s a little snippet from the Create A Language Clinic chapter on Case (Declension).
Using Case As A Worldbuilding Tool
Letâ€™s play with a sentence in English, creating a couple of new cases to reflect a society very different from our own.
Creating A Case (or Two) for the Government
Letâ€™s say that weâ€™re required (by law, religion, or mind control) to publicly speak to and about government officials in terms of deep respect. Further, letâ€™s say that we wish to speak of them among ourselves in, ah, a somewhat less reverent manner.
Weâ€™ll create the reverential case and the despicable case specifically to discuss government officials.
Weâ€™ll create two case rules to make it possible for us to carry out these new goals for our language:
â€¢ Reverential-case nouns end with the suffix â€“ba (singular) and â€“bat (plural) and reverential-case verbs begin with the prefix bâ€™.
â€¢ Despicable-case nouns end with the suffix â€“duh (singular) and â€“dork (plural) and despicable-case verbs begin with the prefix dâ€™.
Now letâ€™s do a sentence, modifying it both ways. The basic sentence will be:
- Senator Hypocriticus addressed the Assembly on the subject of raises for members of the Sentate.
We can tag certain nouns as neutralâ€”that is, not in need of modification. Well, really, we only have two neutral nouns in that whole sentence, and those are the words subject and members. Everything else has a political charge thatâ€™s going to require modification. 
Reverentially, (what youâ€™re going to hear on the nightly news, for example,) weâ€™ll get:
- Senatorba Hypocriticus bâ€™addressed the Assemblyba on the subject of raisesbat for members of the Senateba. (grovel, grovel)
The guy at home watching this on television is going to turn with one eyebrow raised and says to his wife:
- Senatorduh Hypocriticus dâ€™addressed the Assemblyduh on the subject of raisesdork for members of the Senateduh.
Same words. Same informationâ€”almost. We know that in the first sentence, the speaker is sucking up, whether by inclination or by compulsion. We know in the second sentence that the speaker disapproves of almost everything said by the first speaker. The word raises could be considered a neutral word, too; in most cases, raises are happy things, and everyone loves to get them. In the case of government officials voting themselves raises, however, the word takes on blood-pressure-raising qualities. Because of that, we can treat raises in this instance as a special case involving only government raises. In which case, we modify it. (Which is, by the way, the nice thing about making up your own rules. They always work out the way you want them to when you do.