Why won't Brendan leave the house? Why don't his folks help him if he's really depressed and not just bummed out? Eventually he goes outside, so does he just "get over it" in 3 months? Is this actual mental illness or things just didn't go his way and he's sad? Brendon is a college drop-out who has lost his motivation to do anything much other than get up in the morning. He eyes his guitar on the shelf but with everything going on around him, his parents, the world, he just can't muster the energy to care. He's definitely in a depressive state - he tries to put on his shoes and find the motivation to get out when the parents announce their divorce, but he's too scared. It sucks to stay inside and hide in his bed but it's a life he's grown to be comfortable with. Ultimately, it's just easier not to take any risks. He has **** parents. They only care to argue and not bother to help their son. They don't know what to do about him anyway, and they don't have money to get him help. Conor is his eventual motivation. He watches his brother pick up a hobby that he once found love and joy in, he teaches him about his favorite bands and he tells Conor the best part of his day is talking to him... he sees Conor actually doing something with his life, taking risks, and it inspires him. When Conor and Raphina announce their departure, it's finally enough to give Brendon the motivation to put on his shoes and leave the house because it's important to him to see his brother off after watching his brother grow these last few months. It gives him the push he needs to grab his guitar and try to find joy in himself and his life again.
Why do the parents split up? An affair? Brendon literally tells Conner a story outlining the fact that the parents never loved each other. They got pregnant and were "stuck." Financial hardship only makes it harder. Both of them sitting at home most days of the week with nothing to do but stew and argue. The mother only works 3 days a week and when she is at work, she's cheating on her husband with her coworker.
Why does Barry (the bully) kiss Conor at the beginning? Why does Conor not react? Why is it dropped entirely, never addressed and never happen again. Barry tells Conor that he hears Conor is gay and calls him a fairy (or something of similar term). I assume the kiss is used as an intimidation tactic, showing that Barry isn't afraid of anything or anyone, and will do anything to have the upper hand.
Why should we care when the sister says she doesn't want to be an architect and throws her books on the floor in anger? The father states that Anne is their only hope. He's put all of his finances and resources into her education, and he wants her to follow in his footsteps. It's an immense amount of pressure, and she's doing it to "save the family" but ultimately can't take the pressure anymore and just wants to go live a life of her own.
Why is Brother Baxter such a bully? All Christian Brothers are not like that. Does he have ANY motivation? Brother Baxter is pleasant to Conor at first, but takes a sharp turn once he sees Conor disobey him by not procuring black shoes to stay within policy. It's obvious BB is a "rules man" and will NOT tolerate a step out of line. Once he sees that Conor is testing the rules in more ways than one, he decides he must do everything possible to make an example of Conor.
There is a scene between BB and Eamon's mom where she puts BB in his place for ratting out Eamon to his father, and that his father hit Eamon because of BB. My takeaway here is that BB is another life-long bully that never outgrew it. Once someone crosses him the wrong way, that's it. The mother is finally stepping up and saying this is not okay to treat kids this way.
And, I still have no idea what Raphina's story is..
She literally says they left her dad and her mom is in the hospital due to mental issues. She was sexually abused by her father. I think that's enough to paint a picture that she didn't have a happy childhood, and thus her willingness to leave for London with a much older man to escape her prior life.