Responses
I don't think byul is going to be a dominant omega, mainly because the author said the story was going to be Alpha x Alpha. Furthermore, beautiful Alphas also exist, I don't think that Byul has marked feminine features and I do notice the mixed features between hye and dojin, nothing to do with Chowon's beauty. And byul is neither small nor short, it's simply that Siwoon is too tall and big for his age, and if you notice, Hesson and Dojun's daughter is also Alpha and she is shorter than Byul. But you made a good reflection.
hye sung was a late bloomer recessive omega even though he was supposedly an "alpha" he had a false diagnosis, even before he had his first heat it was evident that he did NOT look like an alpha. Byul is supposedly a DOMINANT alpha but he appears very effeminate looking and hes not very tall for a DOMINANT alpha (5'8) I know hes just 17 but if you compare his physique to the other alphas around his age hes significantly slimmer. AND if we look at dojins side of the family where they're all alphas they dont look anything like byul. we're familiar with the omega body type being like chowon and hye sungs but its NOT the only physique an omega can have. For example in one of the side story where hye sung would blush around omegas some were not as petite as him and could pass off as a beta and so could lee seung-ah imo ( do-gyeoms lover). Also with dojin being a dominant alpha and hye sung being a recessive omega I think there is a possibility that hye sung could've passed down some sort of gene that caused him to be diagnosed as an alpha before being a recessive omega. You could use the argument that hes obviously an alpha because unlike hye sung hes not as small BUT I really think there's a chance hes a dominant omega. This story just started but from what we can tell some people around byul were surprised he wasn't an omega and instead presented as an alpha. Dominant omegas are meant to be breathtakingly gorgeous and domineering, which idk about domineering but byul is very pretty in the same way chowon is. The way his face is drawn is very reminiscent of a dominant omega. Also in the beginning of love is an illusion when hye sung first gets pregnant the doctor says the probability for him and dojin to have a baby was extremely rare, almost worth reporting to the academia. That's how rare it is for a recessive omega to give birth to a dominant alphas baby.(it was thoroughly ignored even after hye sung got pregnant the second time bc of herbal medicine it was still rare even if it was brushed over cause this is byuls story not his parents) I think hes a dominant omega im not super good at the Punnett square bs but for being an outcome of something so rare I think it would make sense if he was an omega like his mom and dominant like his father. just food for thought tho and what I noticed while reading.