Oh I am so sorry you feel that you feel you're not doing enough. 
I don't feel your posts are reactionary, I always look forward to them eager and curious at the innerworkings of Arn's mind.
Maybe your reactions are more responsive in a sense as of late, but that is because I have to set you up with bits and pieces of plot and information, not tidal-waving you with all sorts of history or lore, so that is doesn't become a 'lore fest' and also  because I don't want to spoil too much (which I know I am going to do if I start blabbing; about what happened at the end of the Sorcerer King's final battle or why and how the Sorcerer King came to be in the first place.)
 
I am still trying to set the pieces on the board so you'll know the players involved. 
But you're more then welcome to add more pieces to our little story or add in your own motivations and plotlines (it was why I suggested you'd bring Toby back in) since it will give you another character to shape his goals/future for like I said you can build plots of your own. I mean Arn and Toby must have had plans aside their Shooting Stars occupation? 
Naturally Eilis changed all that in Arn's case, but maybe Arn himself has some skeleton's from his past coming to mess things up as well.


Also I hope my explanations of the sides; Vaim's Empire, the Tahjai and the involved individuals are clear enough? 
Maybe I should post a bit more background info here in the OC so you can play around with it as well or add your own enemies to our list.
All the puppets I am currently stringing along will have their purpose. Ravros or Scylla aren't easy villains, they're meant to be rather grey, just like Uilles is shown to be fallible. 


As for Arn and Eilis. Arn is connected to her, regardless of the other side. The problem is is that 'that other side' currently doesn't care about You, Eilis or Belisio for that matter.

But it can be influenced, talked to, even persuaded, provided you wish to try that out.

You could also go the opposite route strengthen Eilis, this other side is so dominant because Eilis herself isn't. If you strengthen her mentally either by word or magic you can achieve the same thing as well, however keep in mind that this would be a constant struggle for Eilis since it doesn't really accept 'its state of being'. (I know I am being vague but I want to at least surprise you somewhat).

Then there is the let it ride out she'll tire eventually approach.

And last but not least you can go into the Thread and try to battle it there. 'However' I must state that it is pretty much like 'warging' from GOT, you will be entering Eilis's body/mind in order to combat it. Result of it is your magic will also activate the bindings, thus causing pain for her just like 'the other' does when it uses magic.
Also you'll be very vunerable if your body dies in battle you'll be stuck in Eilis as well and you won't be able to help Tyrhallan and Uilles.


Hopefully you don't feel like I am hogging all the storywriting, cause I wouldn't be able to do this without you. Again don't be afraid to go crazy, you might even decide to kill Eilis, but it will be over rather quickly then...
I just hope you don't see our writing as a chore, like something you have to do, but enjoy it as much as I do.
Anyway I rambled on long enough again...
Just let me know what you need of me I will give you as much information as I can without spoiling the plot, unless of course you don't care for surprises I will roll out the entire plot then should you wish to know it before hand.