this trope never gets old for bmkai!!

bg going to bed that day (exhausted from the trip and catching up with his family/friends; he thinks he's going to go straight to sleep once his head meets his pillow but his mind can't help but wander to dangerous territories in his brain: kvi, his sweet dongsaeng kvi that is now an alpha, strong and charismatic and towering over him, making him feel stupidly small & jittery)

personality wise he's still the same which just makes it all the worse for bg, because why is kvi the perfect alpha!
sweet and caring, he wasn't arrogant or aggressive (the way alphas were stereotypically) and his inner omega couldn't look past the fact that kvi was physically strong enough to protect him (bg recalls their first hug after they met, bone crushing with bg's face squished in kvi's chest but he felt warm and safe in the younger's arms)

he had anything an omega would want from an alpha mate ( .. a mate that could pin him down and scent him and breed him, provide him with the perfect knot and even more perfect pups ...)

(that's how bg's thoughts end up triggering his preheat)