Rhaast, the Dark Star and Ora

Now that all of this has settled in, I think it is worth questioning how Ora works, at least when paired with things like Rhaast, a corruptant.

Rhaast is quite different from the rest of corruptants, as not only is he trapped inside a scythe (although that could be related to the Ora Gate, haven't found that lore tibdit in the pre-game lines), but also he has a clearly defined personality, opposite to Dark Star Thresh, that is a being devoid of emotions, what made a pretty bland announcer voice.

Even after taking Kayn's body, Rhaast seems quite different from the rest of corruptants, but based on Dark Star , and Dark Star 's lantern, a Dark Star that devours lots of matter becomes red, and the corruptant also get golden pieces. This leads to the question of what ora really is, and how does it interact with the Dark Star. Is ora only a fuel for beings, acting like a substitute of matter for corruptants, or it does bring something else to the table, explaining Rhaast's mutation?

Kayn also becomes a celestial when absorbing Rhaast and all that ora, that also leads to the question of wich factor fueled this transformation. Is ora part of the composition of celestial entities? Or is it because the ora "purified" a corruptant like Rhaast into his "enemy", a celestial being?. I'm inclined to believe the second one, as if Kayn was transformed by ora itself, it would probably be yellow and golden instead of blue.

What is Rhaast? a very special corruptant? or a mutated corruptant "contaminated" by ora? Why does he fear the other corruptants so much? (Although i can kinda see the reason for this last one)