After viewing Season 1 of Defiance, I got a very unpleasant impression of the Castithans.
Datak Tar and his wife Stamha, plus Castithans in general, I started to wonder if they were not very nice people (both individually and as a culture).
I won't recount what they did, but every action they took was either devious, murderous or motivated by greed.
Stahma was harder to read then Datak, given that she seemed to be genuinely compassionate towards Christie.
However, given what she did with the flask in the episode Everything Is Broken left me as to no doubt how ruthless she could be if properly motivated.
Alak Tarr seems to be the only one who is at least honest and decent, which may be attributed to the fact he was raised on Earth amongst humans.
I'm not going to shed any tears if Rafe McCauley decides to shoot Datak and Irisa stabs Stahma.
It's unusual that most of the Votanis Collective made an effort to get along with other species, but the Castithans continue to hold themselves apart.
It's scary when the lawless rebels (Irathient Spirit Riders) are more trustworthy then a proper upstanding civil culture.