Don't plan on playing any of chp 11 until it's all released, and obviously I don't know where Neon is going with his characters or story, but it's interesting to think about the politics and day-to-day challenges of jobs like this. Not defending corruption, dereliction of duty, or outright abuse or anything like that, but my understanding is that sometimes, an officer can find themselves stuck between a rock and a hard place with no easy way forward. And sometimes things aren't as they seem, either.
Expanding on what
DiTo said, I would argue that the guy who's really angry and emotional could be the kind of guy who's passionate about his job and, in my eyes, less likely to be the corrupt informant. Likewise, the guy who's calm and seems reasonable could in fact be the stonecold asshole who doesn't give a shit about his job or principles; that's kind of how I'd expect a corrupt cop to act. Of course, even then, he could have reasons for doing what he does... maybe he's trying to get cozy with Lucien to see if he can find bigger fish? Or not... probably not, but just something to consider.