using ru

[omumyu]

I have been studying na'vi for several days now and I still don't really understand the purpose of ri and ru. Can somebody help me out?

Irayo

[Tanhì'itan]

Kaltxì Tsuktu, oe pa<ol>wm fi'u.
Hello sibling, I asked this.

I asked a similar question in the topic prior to this, I still await an answer. I am confused as well, any help would be appreciated.

[omängum fra'uti]

The dative (ru) is the indirect recipient of an action.

Oe-l tsko-ti taronyu-ru tìng
1-ERG bow-ACC hunter-DAT give
I gave the bow to the hunter

The topic (ri) is context for the sentence.

Fì-skxawng-ìri tsap'alute s<eng>i oe
About this moron, I apologize (make apology).

In both cases, you should be able to take out the dative or topic and the sentence means the same thing, just without context.

Oe-l tsko-ti tìng
I gave the bow (To some unknown recipient)

Tsap'alute s<eng>i oe
I apologize (For some unknown reason)

[Coda]

Would the dative case apply to idiomatic verbs like tìng nari and tìng mìkyun? Or would the more common accusative case apply?

"fì'tìroliru tìng mìkyun" or "fì'tìrolìri tìng mìkyun"

[omängum fra'uti]

You're actually doing topic vs dative there not accusative vs dative.  Often the topic can be used in place of the dative to carry the same meaning, so if one of those is correct, they probably both mean the same thing.

Idiomic verbs, including pretty much any verb phrase made using "si" are currently an unknown in grammar.  My feeling is it it would stand in as a verb phrase, so would use it like it was a verb on its own, including transitivity, datives, and topics.  But like noun phrases, verb phrases are something we don't know about the grammar at the moment.

[Tskxäozì Ewaoe]

Again, I say this many times: Try out Skxawng's grammar worksheets.
Note: -ri marks the Topic, -yä marks the genitive (think of it as an 's) and -ru marks the dative.