Is he going to kill them why is he looking at them like that

No, I think he was thinking of his own mother in that instance. Like how the mother clinged to the child just as he clinged to his mom. But this child said that he hated his mom. So he probably thinks that the child is ungrateful.

I believe he's jealous of how loving the mother is or is either thinking of his own childhood.

Y'all smart. Or maybe I'm just slow