I really would like to know, when they bonded?
Like the last time they were together or before the birth of Byul?
That time it felt like they connected at least a little bit.
Dojin knotted hye sung. In some omegaverses that's the form of bonding
It's just my opinion but I feel like they bonded after Dojin knotted Hye Sung. If it was when he knotted him then Hye Sung disappeared for too long after that and it would've had an affect on his health but since that wasn't the case his health was fine.
Fargo says that the bonding thing isn't physical
I like how the relationship between Heesoo and Hyesung ended in this bickering siblings way. It's like me and my brother then we were younger.