
i have a hunch that they're fated pairs. Ive read many omegaverse with this concept and the first thing that attracts them are with pheromones. Taeju and Euihyun have the same scent and taeju's scent have a calming effect to euihyun's body even though they just met (during earlier chapters) during his suicidal days. Plus, it is impossible for euihyun to be vulnerable to Taeju's scent unless his senses are already familiar with it or if they are fated pairs.

wait, so there are two dads and one mom?? is that their parents?? IM SO CONFUSED

Yep. You got it. As for the chapters they are in, there are some kind souls who listed their sightings further down in the topics from your comment. That's also how I found out dark-haired grandpa is the one who gave birth to Taeju. Since both his parents were alphas, it was hard to do.
So this is an omegaverse where anyone and everyone can potentially have a baby if they just try hard enough.
this is an escape from the cruel reality that we have right now this is one in a million chance to experience haha damn