While a not is known about April and Noah's background, April did reveal hurt feelings over the fact that after their parents immigrated from Brazil, they put all their money and focus towards Noah and making sure he studied Medicine.
Noah made a lot of mistakes during his first calls and April went out of her way to help him. Kelly, who was her childhood friend and fling, told her that she deserved to be a med student much more than Noah did and that if she wants to do that, she should, because she's much better and experienced already. April refused to and said she didn't envy her brother.
He and April share a close relationship, as she usually helps him out when he's struggling, and he tried to help and comfort her when she had a miscarriage.