-Spends his childhood displaced and committing countless atrocities for the sake of revenge
-the killings he has done while blinded by rage eventually catches up with him and he has to deal with the consequences
-is in a constant battle with his inner demons
-wants to find peace but is constantly haunted by what he has done
-lost countless people who are close to him because of his true nature
-is constantly hunted and fears getting close to others because of the danger he can bring to them
-wants to protect the weak and do the right thing but is feared and shunned by the general public
-is haunted by the memories of those he couldn't protect since he knew the consequences of getting close to them
The Elric brothers
Trafalgar D. Water Law
-Contaminated with a life-threatening disease when he was a child
-Lost all of his friends and family by a raid
-Again, lost someone that became important to him
-He was in a condition where he was unable to survive for long unless the cure for his affliction to be found.
-Hates the world
o shit we goin into detail?
-his world is in a post ice age climate
-parents killed at a young age and people held him hostage, cutting off his limbs for meat
-after he escapes he had to cut off his arms and legs repeatedly to feed himself, his sister, and the village
-his sister is his world, and he has to fight with creepy incest feelings toward her
-his village gets raided and everyone, including his sister, is burned alive by a fire that can not be put out until the source burns to ash
-before his sister dies, she gives him her regen powers so that he may 'live'
-his regen powers are so strong the fire will not kill him, so for 20 years hes left on the snow in unimaginable agony, until finally his mind breaks and hes able to stand
-only the thought of revenge allows him to cope with the pain
-he finally meets the man who did this and now hes just a weak, scared old man
-he accidentally burns down an entire town, killing thousands of innocent people
-the one person he finally got close to dies because she touches his flame, she also tells him to 'live' even though he wants so badly just to die
-multiple suicide attempts, none work because of his regen abilities
-has to struggle with wanting so bad to die as his existence is simply agony, but everyone telling him to 'live' and it haunts him
im probz missing more but iv never seen any character suffer like him
Definitely Subaru from ReZero, that dude’s whole life is centered around pain and unhappiness.
Madoka because being Madoka is suffering apparently?
Eren Yeager seems like an honourable mention.
From all the anime characters which I know and am acquainted with, I nominate Kyoko Sakura from "Puella Magi", because by actually trying to help her family she unintentionally and unexpectedly caused a chain of events which made everyone in her family die and leave her as an orphan. She was responsible for her own tragedy by trying to become a hero. It's very sad.
I even wrote a poem about her and published it on my Fanfiction.net account.