I'm gonna hold ur hand when I say this— ..... (spoiler) It is actually a misunderstanding. Kwon Ido did not know Sejin was in heat, also the "gift" he was referring was not Sejin. Technically, the jerk brother misunderstood everything, thinking the gift was an omega in heat(sejin), which leads him to grape Sejin. The gift Ido was referring (from what I can remember) was a document? containing of something that can hurt the jerk brother's reputation and wealth, even something that can make him a criminal and go to jail.
Overall, I can not absolutely defend Ido in this timeline bc (spoiler) Ido will also grape sejin out of anger. Rage from the misunderstanding, the fact that Sejin was fucked by his jerk brother. So then he grapes sejin, knots him, and after some time, sejin finds out he's pregnant. Sejin doesn't know who the father is so he kills himself in front of Ido.
(Well, I kinda spoiled everything, so sorry)
What the hell he died with the baby noooooo!!!!!! ╥﹏╥
What are you talking about?
Oops nevermind I spoiled myself
Sorry bro (￣∇￣")
this must be intentional cuz why would Ido purposely let his brother get the gift in the house? feels like a trap and he must know his heat was nearing