Ryan seems like he is quite a paternal man, look at him adopting Karis, all the tings he did for his nephew and his loyalty/affection to Christoph. In all of those relationships you wouldn't expect the type of devotion that Ryan shows, but he puts him self out there, damaging his own health and not getting much in return in order to protect those he holds dear.
Also, Ryan, due to his status as an ex hunter (current involvement hidden) probably is on guard constantly, especially seeing as his family were poisoned. He's not stupid, and eventually probably did come to suspect Christoph, but needed conformation from the top ie Edwin, rather than just behaving reactionally.
It would be interesting to see Christoph's perspective, so he doesn'y just get painted as a sleekit wee traitor. Kyon was groomed and manipulated by Edwin to destroy and kill, so Christoph is likely the same. Maybe Christoph's parents will have an important part to play in the upcoming development, as unlike Kyon who was orphaned, it only say Lucaon is mixed blood. Maybe he was rejected by his family because of this, maybe he has family working at intron. Or maybe because of his mixed race status and rejection, Christoph grew to resent the Royals and joined Intron of his own free will, but when he started to work with Ryan as a servant, he started to grow fond of him which made him struggle with his loyalty to Edwin/Intron which is why there was that kerfuffle when Edwin tried to bring Christoph back, and Chrisoph killed one of Edwin's team.....
We'll see, we will have patience and wait *lies on the corner* _(:з」∠)_
Christoph's is Edwin's son, most probably... Edwin told Ryan to look at him (Edwin) and guess who the traitor was, and then we were shown Christoph has Edwin's eyes. He's most obviously his son.
You are 100% correct. It seems like ryan who only cares about lucaon and sihan as son, has now Christoph treading over his heart. Just look at the way he looks at him
............pish, for some reason I doubt Ryan didn't know the truth, he is probably "I know but it's okay, I won't say anything" kind of person. I mean look at Ryan, he's like that one smart character who knows everything that we can find in certain anime. He was probably blinded by Christoph's.....ummm....cuteness maybe? Oh well, surely there's a reason. For now, I just hope he won't die or something.