
Yes, Ryan seems a pretty decent character. He basically sacrificed his health for Lucaon resulting in him having to sleep/recover for years, and now he is apparently doing the same for Christophe. He has been a father figure to Sihan, and obviously cares a lot for both Sihan and Lucaon. Sihan too must have similar sentiments as he keeps a photo of him and Lucaon as kids with Ryan, next to his bed alongside his only other picture of a relative (his partner). For Ryan to poison/try to kill Lucaon who he viewed as family, in a traumatic and painful way doesn't add up. Any motivations for him to be the culprit haven't been displayed... so far anyway.

Yes, it would be interesting if more of his back story was provided (think all that has been mentioned is that he is "half royal blood" and who he has worked for). Don't think there has been any first person narrative from him, or any real insight into his emotions . It would be easy to assume the obvious "bad guy" characters like Edwin and his organisation, but Christophe being the culprit would be a good twist and everyone, especially Ryan would be devastated.
Idk i dont think Ryan's a culprit(actually more like i dont't want him to be) i mean, I felt a little bad for him when he asked Sihan to call him dad, I think he really does care for lucaon and sihan a lot, that's why he was forcing Kyon to leave lucaon, he was scared, idk why u guys suspect him