Responses
I though that his sister looked like Rain. Even though Christoph and Rain look alike
Yeah, that's true too, but I feel like the similar imagery they were showing between Christoph and his sister might have been signifying they were related. Either that or it was just showing that Christoph reminded Ryan of her because he was someone he cares about who ended up getting involved with the VS solution.
The resemblance to his half-sister is pretty uncanny. Either possible incest (which was normal for royal families in ancient times to maintain the "royal bloodline" even though it lead to a lot of birth defects), or maybe he's just his great great nephew or something. Either way, super sad shit, it's just one thing getting better another getting worse with this story lately.