aixamee's manga / #Yakuza seme(2)

Chap5+5.2 - start with strangers and ended becomes lovers

Love the starter story, but confused me in the middle story, Min Joon just love the dad's kid after just seeing him so hot? Toma is adorable kid, who doesn't love him like Joon is, but Daiki so suddenly felt love toward Joon is so weird, when is the exact time or event Joon become the really important person to Oyabun? Plothole.