Wouldn't the easiest alternative solution be, that the champ just tells Argoth about Kassyra?
Arona and the orcs don't really know why they just wait in the camp. Argoth "knows" that there will be a great challenge and glory, but doesn't know exactly what it is.
Quick summary: You go to Argoth, tell him about what happened at Winter City and now the orcs have a clear foe and goal. Now Arona also joins the team.
A bit more fleshed out: Clear Winter City, meet Arona in the field. You tell her that you need to speak with their leader. Maybe have a fight, she wouldn't let you meet Argoth that easily. Then you go and meet Argoth, tell him what happened at Winter City. He doesn't trust you and sends Arona with you, to testify your claims. Now you show Arona Winter City and go back. While the two of you are gone, the tribe gets attacked by demons. On return you help fend them off. Now Argoth fully beliefs you and realizes how fucked they are. He promises not to raid the lands and prepares for upcoming battles. The orcs have know a cause, willingly stay at the camp and the situation is diffused. Arona still doesn't want to stay at the camp and you can ask to her to join you.
This can also account for future events: Like helping at lifting the siege of Khor Minos or the assault on Alissas keep. Or even reinforcing Hawkthorne while the champ is gone.
Edit: As an alternativ ending, the demons could kidnap Argoth and Arona becomes the new chief. Or if you really REALLY wanna do him dirty, let him be turned into a super submissive bimbo, who is now the camps bicycle.