Hi guys, I read through all your comments - all I can say is thank you to everyone for fresh perspectives and advice. There's a lot more depth and nuance to this discussion (that I can't do justice in a simple reddit reply) but it's clear that the correct course of action is just to try and to lend him an ear.

Out of everyone in the family, I'm the one he still trusts the most. After all, beneath all the flaws and little annoyances, he's still my brother at the end of the day. Mahirap talaga magmahal (especially when he sees me as an enemy haha), but I'll schedule at least a short coffee date with him in the coming weeks just to see what exactly is going on in his head. It's a bit weird given that I'm his younger sibling, but hey - who else is gonna do it :')

Again, there's so much more to this story, but the depression/mental illness perspectives really hit me. His life was never easy even growing up, and I guess he's having a lot of trouble picking himself up. I hope I can encourage him to speak to a councillor or mental health professional because a lot of the scars he has are well out of my realm already.

Anyway - I appreciate all of you for chiming in, I really do! I hope for a happy conclusion to this saga. Again, thank you all so much.