There is a saying in Tibet that "tragedy should be utilized as a source of strength." It just so happens that in Attack of Titan, there's no shortage of tragedy. As such, there's also no shortage of strong characters in that anime. Those who have experienced immense loss have become some of the toughest characters in the series. And while emotional fortitude is commendable, it's far from celebratory considering its source. At times, these characters are even bordering on superhuman when it comes to dealing with their disheartening backstories. Now that Attack on Titan is nearing its end, it's time to look back at how some characters became who they are and what kind of misfortunes they had to handle.
10 Reiner Braun
Reiner being one of the more fortunate characters here speaks a lot about the typical troubles of Eldians, Marleyans, and the people of Paradis. He's a war hero but in truth, he did nothing but lose in Paradis. The fact that he was forced to commit mass murder has also made him depressed come Season 4.
Prior to that, Reiner's past adventures were also revealed and he did a noble sacrifice, volunteering to be the Armored Titan to save someone else from the cruel fate. Deep down, Reiner is a genuinely caring person but his violent tasks as a Marleyan Warrior severely taxed his psyche to the point where he developed a split personality.
9 Keith Shadis
Keith Shadis is the esteemed Cadet Corps trainer and was responsible for recruiting and educating Grisha Yeager in the past as well as turning Eren into a Survey Corps member. Sometime before Eren was born, Carla Yeager was compelling Keith to stop with the Survey Corps expeditions since they were just sacrificing people.
Keith simply couldn't since he's already been through hell and lost many comrades and friends doing what he believes is beneficial to Paradis. To add insult to injury, Carla marries off the very man Keith rescued (Grisha) and also has a son with him. Keith lashed out at Carla after this, which is understandable as he not only lost the girl he loves but also failed to achieve something in the Survey Corps.
8 Dina Fritz
Life could have been great for Dina Fritz since she's a direct descendant of Ymir and King Fritz and she possesses special spinal fluids and Founding Titan candidacy, but she was born on the wrong side of the Paradis' wall. Hence, she had to keep her heritage secret so that Marley wouldn't weaponize her.
Despite all the caution, however, Marley's cruel military still managed to catch her as a rebel after being betrayed by her own son; she was promptly turned into a regular titan. Dina would go on to wander the wilderness of Paradis until she's eventually killed by Eren Yeager.
7 Kaya
Kaya is but a side character in Attack on Titan but she's actually suffered some of the worst traumas ever in Paradis. It's on the same level as Eren's childhood predicament but a bit worse since it's not just her mother that was eaten but also other family members. She's the girl whom Sasha Braus saved.
As a child, Kaya saw her mother gradually being eaten by a small titan. She was so in shock that she barely knew how to talk or move. Thanks to Sasha's intervention, Kaya's mother's sacrifice wasn't in vain. Hence, Sasha became Kaya's own personal hero but sadly, Gabi Braun had plenty of bullets and words to say about that.
6 Zeke Yeager
For some, Zeke probably doesn't deserve to be here since he's had a life of relative comfort in the Marleyan military. There's also the fact that it was he who chose to betray his parents, Grisha and Dina, and turned them over to Marley (effectively causing Dina to die).
However, Zeke's most recent conversation with Grisha Yeager during the former's time-traveling escapades with Eren revealed that Zeke was wrong to betray his parents. Initially, Zeke thought his father didn't love him but this wasn't the case as both of them were under extreme stress due to being Eldian rebels within Marley. In the end, Zeke probably had the biggest regret out of all the characters in the anime.
5 Survey Corps Ymir
Other Eldians from Marley aren't as lucky as Grisha who got to inherit the Attack Titan right away. The fake Ymir had to go through a prolonged state of hibernation before coincidentally waking up with the Jaw Titan vessel standing on top of her. In a sense, Ymir still got lucky.
Prior to that, however, she's had one of the worst struggles as an Eldian in Marley. Some cowardly Eldians made her the scapegoat by worshipping her under the pretense that she's "Ymir" only for her to be singled out for execution since she's the supposed religious head. That explains Ymir's cold and loner behavior. It's hard to trust people after that.
4 Eren Yeager
The protagonist and main driving force of the show, Eren Yeager has been through a lot both physically and psychologically. His final memory of his mother, Carla is Dina Fritz's titan munching on her. Eren also killed and ate his father Grisha, but he was made to forget that memory.
All of that was enough to drive Eren to become a vengeful young man who's hell-bent on seeking justice for all the atrocities and cruelty against the Eldians of Marley and Paradis. It's understandable how Eren became what he is today though by no means does it excuse his genocidal actions.
3 Grisha Yeager
When it comes to the struggle to live and survive, one might even consider Grisha's story as more incredible than Eren's. As a child, Grisha's sister was slaughtered by a Marleyan officer and his parents did nothing about it. Thus, Grisha swore to bring the Eldians back to power, only to be betrayed by his own son, Zeke.
This resulted in his getting tortured and his wife also got turned into a titan. He was given a second chance but had to forsake his first family and create a new one in Paradis. Too bad this family also got ruined and Grisha's son also forced him to kill the royalty of Paradis before finally getting killed by and eaten by Eren. Zeke was terribly wrong, Grisha unironically deserves a father-of-the-year award for redeeming himself.
2 Levi Ackerman
Despite having "Ackerman" in his name, Levi's life wasn't privileged. While other characters' parents were eaten and killed by Titans, Levi's mother died because of society's flaws. She was an Ackerman reduced to the life of a prostitute in the Underground city who died of an unknown disease while taking care of a very young Levi.
Witnessing his mother slowly die and his emotional support fading away, this scarred Levi for life. The resulting prolonged period of starvation afterward was what probably stunted Levi's growth which explains his short stature. Kenny Ackerman, Levi's uncle, did rescue and look after Levi for a while, but it was hardly familiar care or treatment and he soon left the malnourished boy to his own devices. After becoming an adult, Levi was never out of the woods as he kept losing his best friends and closest comrades, including Erwin Smith.
1 Ymir Fritz
If a person has the power to turn into a giant, one would think that they'd crown themselves as a god or monarch, but the real Ymir was a little too timid for that. Her backstory was recently unveiled in the anime where she experienced all kinds of injustices at the hands of the first King Fritz. She's a slave and her own king tried to have her killed.
When she came back wielding the titan's powers, she was turned into a weapon. Even as she sacrificed her life to protect King Fritz, she was treated like a mere experiment and her corpse was fed to her daughters raw. Even in death, she didn't escape servitude as she was still being ordered by Fritz and his descendants to keep building titans. To Ymir, giving Eren access to the Founding Titan and the Rumbling was a taste of freedom sweeter than revenge against the world that wronged her.