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Can someone explain the whole story I don't get it
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So basically, Sangyul used to be a lab rat and is ought to be made an omega to be sold for money but they failed. So he's only made to experience what a real omega is experiencing (e.g. oversensitivity, getting wet down there behind) for the same reason[money]. Mr. Han eventually offered him to the alpha Prince because they both have unique traits and for that pharmaceutical to gain power from the royalty as well, deceiving the royal family in the process.
He was sent to the palace with the illegitimate son of Mr. Han, disguising as Sangyul because no one knows what Sangyul really looks like and the wedding will be called off anyways, so they planned to deceive the Prince until the engagement ends. The son used this opportunity to make a use of himself for his father because he's a good for nothing. Also, the reason he was sent to accompany the fake Sangyul is because they also want to know what will happen if he's exposed to an alpha despite failing the experiment on him.
So... they fell in love, the Prince made a plan to drag Mr. Han down and everyone who made Sangyul's life hell. They get married, and live happily ever after.
He's toxic af like whats the friking point of this he's just going to keep him by his side with no label??? This is bs