Yes, that's right. The first time they had intimate sex, Hyeon saw the tattoo on Ian's body, but at that time Hyeon might have been looking into Ian, but I'm also unsure about Hyeon's own thoughts.
Hyeon is very unpredictable, but I have an instinct that maybe Hyeon actually already knew that the Ian in his house right now wasn't the real Ian...( ̄∇ ̄")
But I could be wrong(◞‸◟ㆀ)

I think they are both good people, but I'm also curious what would happen if Hyeon found out Ian's true intentions... Because I think Hyeon really hates being lied to...
Besides that, why does Hyeon look so innocent and trust someone so easily, oh my god, for a gangster he looks softer than any gangster I've ever read about huhuhu
And the last and very important thing is why Hyeon's face looks like (Jaekyung) lol