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I don’t know about the lemon scent, but I think the secret isn’t that Siwoo is an omega but it is linked to Byul’s question: what if, when they were younger and Siwoo had a crush on Byul, he tried to confess by kissing him or something and was rejected due to the brainwashing? He might have been hurt and started to keep his distance because of that… then again, it might also be because of the omega part of the question: he likes Byul but he doesn’t think he’d be liked back precisely because he’s an alpha and because of that the question feels like rubbing his unrequited love in his face??? Idk alpha/alpha and unconventional abo dynamics make for interesting possibilities too
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pretty sure he's is an alpha, a strong one, and the reason he avoided Byul all this years was because he was in love with him and Byul being an alpha automatically meant that they couldn't be together (alphaxalpha are unconventional couples) so he avoided him to stop his feelings, pretty obvious
For once that Fargo is doing an alphaxalpha don't ruin it
'LEMON SCENTED FABRIC FRESHNER' --- That wasn't fresher Byul, THAT was Sinwoo's omega scent, Sinwoo is an Omega. He probably hides it at school but cant do much about it on his own bed. That's why he got weird when Byul brought up 'Kissing Omegas'. Sinwoo always seemed like he's a secret, he's an Omega and Byul will be his Alpha ヾ(☆▽☆)