Elis is the legimate heir even if Conrad will find out Alaina's schemes. Are you sure you can trust Alaina to keep you on the throne once you tell her you want nothing to do with the elves, if so you wish?
Elis is illegitimate because his father is illegitimate.
If Conrad finds evidence, he will be the next king because Cass is a woman.
I repeat, I don't dispute that Alaina wants benefits for the elves from the human emperor. That's obvious.
Obviously, if you tell Alaina you don't plan to give the elves anything, she'll be disappointed.
But personally, I plan to give the elves at least a valley and rights.
I repeat, Alaina's adventures are far more daunting than Elis.
Alaina knows how to kill, manipulate, pressure, and deceive entire nations.
With the resume she laid out before the fireplace, the CIA would beg to hire her at any price.
Her help will be invaluable when Alice wants to legitimize her harem.
We just need to find out whether she values a republic, or whether she'll help build an absolute monarchy.
If it's the former, then she needs to crack her skull with a goblet right now.
If it's the latter, then she'll be more helpful than anyone.