Curate, connect, and discover
I think we should take more time to appreciate the cruel irony in so many of the bsd backstories, because Asagiri has this way of writing that's not just "oh sad things happened to this character." They're twisted, each in their own special way.
Atsushi: His whole life, he was treated awfully because he had the tiger. And yet, that tiger is what helped him survive that treatment, it's a manifestation of that will to live he grew because of his abuse. It's the source of all his strength and all his pain. The director told him to only hate him, never to hate himself, and yet, all his life, he blamed only himself for his misfortune. The one lesson the director wasn't trying to teach him is what he learned.
Dazai: At the beginning of dark era, Odasaku has one of the healthiest wills to live. And he reaches out to save Dazai from his own darkness, but he can't. But at the end of dark era...it's flipped. Dazai is begging Odasaku to stay, he's reaching out to stop him, he's telling him to find some meaning in life, that things will get better. Mr. "life is meaningless" himself is trying to tell his friend that life has value because he doesn't want him to go. It's right after he told Odasaku how he knows he's destined to lose everything he desires, and then Oda leaves him because he's lost his will to live. And when he dies, he sees himself as a man who failed to become good, to give up killing, yet Dazai sees him as a success story that people can change.
Chuuya: Chuuya's friends betrayed him because they thought he was betraying them by joining the Mafia. And then Chuuya joined the Mafia in order to protect the friends who just betrayed him.
Yosano: She only wanted to save lives. All she wanted was to help people, to heal them, and yet it was that kindness that ended up turning against her. Because by helping them, she also became the source of all their problems and all their pain. She saved their lives so much that all they wanted was to die.
I could go on for longer, but then this post would be very, very long. There's just something about the cruel irony in each of the backstories that make them all feel so tragic.