I was wondering how he'd end up with them. I imagined it'd have something to do with them somehow being his relatives (it said they were "bound by fate", so...) -- or the twins would use some sort of magical fuckery to end up in his hands.
I didn't expect this result, tho, lel. As if adopting kids is that easy, and that a uni student would just arbitrarily decide to adopt two random toddlers. Gotta hand it to Chinese stories for not giving a crap.