The Clans definitely are not into the whole "rape and pillage" thing.
In Clan society, the "free love" approach means that sex is readily available; among Trueborn warriors, the easiest approach to seduction is to simply walk up to another warrior and ask if they wish to couple (ie, have sex) with you. Within clan society, sex is removed from reproduction; Trueborns are biologically infertile normally. Likewise, there's very little emotion in it; a Trueborn is just as likely to have sex with someone they have known for a long time as they are with a complete stranger, and in neither case would there be any feeling of commitment or affection.
One of the results of this is very little feeling of inappropriate behavior. A commander having sex with a subordinate is considered to be entirely natural and normal, and unlikely to affect their judgement or behavior. An instructor having sex with a cadet is unremarkable, and said instructor is going to pass or flunk the cadet based on their merit, not on how good they are in the sack.
Conversely, in Clan society, rape is seen as one of the worst crimes one can commit. The Clans don't have much in the way of a criminal justice system, and trials are virtually non-existent, relying more on honour systems and honesty then gathering evidence. An accusation of rape - even if the evidence is dubious - is punishable by death. On the spot. In the street. In public. With the body being strung up from the nearest lamp post.
For a Trueborn, having sex with a freebirth (ie, someone born normally from their parents' progreation) is seen as disgusting at the best of times and somewhat akin to bestiality at worst. There are exceptions, but those are few and far between.
In short; a Clanner would be incredibly unlikely to rape a prisoner; they'd be more likely to beat the snot out of them in the name of "teaching the freeborn scum a lesson" and then go off and have sex with a random stranger.