WHO:
Me: mid 20s, lived last 7 years away from home in a different city and then in a different country. I go back home for a week every 5-6 months.
Mother: clinically depressed since her and my father separated 8 years ago. She takes meds, but I don't believe it's a too extreme situation. What I mean is that it's under control and that she works a full-time job, she came visiting in 2 different countries a few times, she takes care of herself. But she's not as happy as she should be
Father: decided to separate form my mother completely out of the blue. He's been a good father to me, and to my brother until the separation, after that he became kind of absent at first (taking my brother only at weekends), then helpless in making my brother doing the right thing (going to school, etc etc) and now he's more present but my brother is also a young adult now, so they have a normal, good relationship
Brother: the focus of this post. He's turning 20 this year - so 7 years younger than me, which is quite a lot. After my father left he was still a kid and he just decided he would do what he wanted. My mother never had a firm grasp on him and could never be authoritative enough. Some episodes just to give an idea: He started high school at the right time, then lost two years because he simply decided he didn't want to go and just stayed home too many days. 3 years ago he decided to completely leave school and go to evening school, but then managed to enroll too late so he lost another year. 2 years ago he started on time but then decided it wasn't his thing. I think you get his way of approaching things. So now it has been around 3 years that he wakes up at 10-11, chill out at home, gets depressed/in a bad mood because there's not much to do and his friends are all working/studying, sometimes goes out in the evening, comes back late at night and then he starts a new day in the same way. And he brings that mix of boredom/bad mood out against my mother having a quite toxic attitude. He doesn't help at all at home, he only cooks - if asked a few times and reluctantly, but leaves everything dirty, doesn't do laundry, doesn't clean the house. Another example: he monopolized the kitchen a few years back with his laptop and it has been there ever since, so every time my mother cooks right after he wakes up, he thinks it's just to provoke him. He is basically a parasite doing nothing. This was much worse a few years back, things are slowly getting better with time but it's still taking him too much time to be a decent person, to start looking for a job, to take a driving license, to do some basic studying. Now he's a young adult behaving like a child. Things get a tiny little bit better every year, but not at the pace they should. To be fair he also started a couple of projects in the last two years with my father (a carpenter), building instruments first and now skateboards, but it never gets to the next step. So he' just treating his hobby like a job and with that excuse doesn't move on to something else.
WHAT:
As I mentioned before my mother is depressive and I feel like my brother is one of the biggest burdens to her. He never got physical, but when in a bad mood/depressed/bored he tends to insult - which happens every other day. Again, nothing too extreme and direct, (more of a "Shit, leave me alone" or "Why don't you do that" kind of thing) but still something he shouldn't be saying. And when these episodes take place, sometimes my mother gets more depressed, then call me to check up on me and have a talk, then tells me that my brother is a pain at home, then starts crying because she's fed up with it and I start thinking of ways in which I can alleviate her life. I'm not too worried about my brother himself, since I believe he will find his way at some point. But I'd like to help him to become better, so he can have a better life as much as my mother can have a better life too.
I tried the heart-to-heart talk, the long letters, the indifference and silence and nothing seems to be working, not even a tiny bit. He's just set on his road and does his own thing. My last resort was the "I refuse to talk to you until you start behaving as a decent person" but it seems out of my place as a brother and kind of childish. Any suggestion of how I could make my brother realize the choices he's been taking have played out quite bad until now and that he needs to start behaving differently (most importantly towards my mother but also towards life)?
PS: Re-reading this is not very clear, but neither my mother nor my father have ever pardoned or approved the bad choices my brother took of not attending school. My mother couldn't possibly physically force him to go to school and my father would bring him some days, the other 95% of the days he was at work and couldn't do it. So my brother ended up staying at home whenever he wanted
PS2: when I'm home things are better and if things start to heat up we usually manage to stop them before they grow. And out of the house my brother is a perfectly functional young adult with whom you can have normal conversations and he even admits his own errors. Which makes it even the more difficult to point out that there's something wrong nevertheless.
PS3: I don't know if it's relevant, but my brother doesn't drink any alcohol and don't do drugs. On the other hand most of his friends go kind of heavy in either one of the above mentioned, and this is one of the things we talk about when together, because it bothers him.
Sorry for the long post and thanks to anyone kind enough to give his or her opinion.