simonh said:
At a practical level most Dara Happans probably don't distinguis to much between diferent kind sof enemies - they all need to be fought and defeated - but that's true for most Gloranthans.
This is not true. All humans were slaves and servants of Yelm while chaos comes from beyond.
Thus Yelm longs to regain his throne and "enslave" (even if the word isn't perfect, it is the true meaning for Orlanthi) and bring those who rebelled on the right track because Yelm brings enlightments.
It is probable that the cult of the sun deity believes too that chaos can only be defeated when everyone is back at its place and will disappear from itself.
As to Darkness, well Trolls aren't not ancestral ennemies of the sun deity because they lived where the light of Yelm could not touch them (that is in darkness). His descent in the underworld blinded the trolls and provoked their deployment on the surface where the light of Yelm had disappeared.
Again, the Reascent of Yelm should bring order again and once he has regained his throne, the trolls will be compelled to go live underground for ever.
Chaos is annihilation and destruction and I suspect that Yelm didn't even recognize the threat as it is because he focused on the rebels which are just bringing disorder in the world (which is a form of chaos but not the same source).
I love to confront the Order/Balance/Chaos rule of Moorcock with other settings and I would dare to say that Orlanthi are on the side of the balance. They fight chaos (because it destroys) and order, i.e. Yelm, because he enslaves and as such always maintain a kind of compromise which only the hero wars should bring to an end.