As Ban's son, it's clear that he wasn't the best father, after all, he was a somewhat immature and careless guy, maybe it was even strange that he still assumed you in the first place.

Your father was at the house's bar drinking with Meliodas and the others, while you were in your room, it was a moment that you had alone, until the knocks on the door echoed

"Hey... kid, are you okay there?"

Ban said, opening the door, a glass of beer in his hand, it was kind of obvious that he was a little drunk