it's his fault for reacting all like that in that first place 10 years ago
Childhood trauma can explain why someone behaves a certain way, but it doesn’t magically erase the consequences of what they do. He was 16, not a mindless puppet his circumstances matter, but so does his responsibility. You can have empathy for what a person went through without pretending every choice they made was justified. Context explains behaviour it doesn’t excuse it.
summer strikw