If you ever catch me calling Aric "well written" I want you to know I am NOT talking about anything pre-TCY I am exclusively talking about the Real Thing. Rhian's death chapter being called Rhian And The Real Thing - which is where he's confronted with the fact that his brother will always choose Aric over him - suggests that the Real Thing refers to Aric and Japeth's love, or could just refer to "Aric" as the Real Thing. The chapter title and quote "flesh and blood" also links to that idea of something 'real', or tangible, Japeth only believes it's real if he can physically touch it, instead of being the illusion of Aric he creates briefly earlier in that chapter. But then you have the fact that that last quote isn't actually from Aric at all, it's from Tedros pretending to be Aric, which implies that everything that "Aric" says in F+B isn't real at all; he's "more real than the real thing", more of what Japeth convinced himself was there between the two of them than of Aric's actual feelings towards him.
There's two interpretations you can get from that, one being that there isn't a Real Thing, that what Japeth thinks was real is a delusion - the fake version of Aric being symbolic of that - and the fact that he only realises it's not actually him is because this Aric is willing to kiss him, and the real thing would never do that. So then the other interpretation is that Aric never loved Japeth - Tedros-As-Aric is "more real", more close to Japeth's idea of Aric than the actual guy, and so everything he says is likely exaggerated. It's possible that Tedros just played into Japeth's idea of Aric, rather than recreating what he knew he was like, since that would've definitely been more effective (and I mean. it worked for a while). The only thing we ever see from the real Aric about Japeth in the entirely of TCY is the letter in book 5, which pleads with Japeth to come and find him, but it never mentions love. The entire Real Thing analogy is genuinely one of my favourite parts of TCY (if anyone knows anywhere else where it comes up other than RATRT and F+B, PLEASE tell me) and is the sole reason why Aric is one of the most interesting characters to look at in TCY. Happy year of the snake everyone