It's quite interesting how this situations ends up happening...
The "naiver" of the two end up getting in the most difficult sittuation to properly adress (his only "easy" ticket to a peaceful life would need a not so smart people to figure out the relationship between Deirdre and everything else in the world).
Arvis' situation became completely unavoidable in the very end, after he became Emperor; but during the beginning; as you explained; he was mostly an unpopular boy that was only really liked for certain people, and Manfroy would take advantage of it; to convince him to "create a better world"... Not exactly an unavoidable fate, but his backstory as a violent person and his fear of being crucified because of his mother's evil blood would be just enough to make him connect with the Loptyr Sect; specially someone as cunning as Manfroy.