What do we know about Malachy McCourt, Sr. that is significant to his character?

Malachy can't find work in Depression era New York City, and any money he does earn goes into the pubs of New York. Angela struggles to feed her family and relies heavily on her Brooklyn neighbors for help. Malachy is steadier after the birth of Margaret but the baby dies shortly and Angela falls into a deep depression. The cousins save the day once more and arrange for the McCourts to return to Ireland and it's here that things go from bad to worse.