Senya hasn't done anything since kotet, so who knows?
Arcann's personality is a hard one to guess, If you don't romance him I get the impression he's sucking up to the Outlander and is letting the Outlander walk all over him because he fears voicing his own opinion (?), maybe time will reveal more but right now I get the impression he's lacking a backbone.
Romanced Arcann wasn't bad but without my head-canon, I don't buy the chemistry between my character and Arcann.