What do you think will be a good tragic backstory for Ominous based on his character?

His page is right here: https://sonicfanon.fandom.com/wiki/Ominous
But if you want read his full personality now, here it is:
Unlike most villains, whose actions are driven by a lust for power, control, revenge, or destruction, Ominous is an extremist who, after seeing all of the anger, greed, and torture that others have experienced, attempts to destroy all hatred, greed, fear, anger, conflict, suffering, sorrow, grief and evil in existence by any means necessary or at least the cause of all of it if necessary, even if it means using dark energy to destroy everything in existence, including himself. This, however, corrupted him into becoming cold, distant and insecure with having a deep and indescribable feeling of bitterness that led him into a somewhat nihilistic and untrusting side on others, including himself, as well as gave him a very cynical viewpoint of everyone, including himself, having a dark side inside each one of everyone's hearts that must be destroyed before it effects each other, themselves, or others and makes things worse.

Unlike Dr. Eggman, who usually has a massive ego, Ominous is very vigilant, observant, sometimes secretive, self-conscious, pessimistic, cynical and self-doubting, as he usually tries not to believe that he is better or stronger than anyone and takes both his allies and enemies just as seriously as they do him, which is very seriously, as well as treats them like a worthy opponent. At the same time, though, he is very persistent and refuses to give up or cower down when being defeated, as he sees it as a sign of fear and torture, unless he realizes what he has done and accepts it with fortitude and guilt.

He is also usually very calm, serious, composed, stoic, patient and affable, though he can be distraught or disgusted. Sometimes when confronted, Ominous would try to get people to sympathize and see his perspective, only to question, call out, and even blame them when ignored, dismissed or disbelieved. Despite this, he can be very admirable, courteous, loyal, and modest, especially when seeing his friends or foes succeed in proving their true potential and he usually takes rejection with a grain of salt. He even willingly decides to give in to his friends and foes requests and help them when in distress and is a person of his word. When he fails to meet others wishes, he usually feels guilty and apologizes in return.

Also unlike most villains who refuse to take their defeat(s) and get distraught when defeated, Ominous chooses to accept his fate because he realizes that he deserves it when finally realizing what he's done. His contempt for evil and torture also has leaded him into self-hatred and inner guilt to the point where he usually tries to punish himself or cause self-harm when he finally realizes that he's doing the same thing that he was trying to stop. He also tries to reject redemption or remorse when he feels that he doesn't deserve forgiveness for being just as, if not more so, evil than who he assumes to be everybody else. This is the reason why he tries to destroy himself along with the rest of existence.

Despite all this, he can be at times merciful when he sees an person cowering down in fear in front of himself and others, due to his dislike for fear and torture and the fact that he doesn't want to repeat the same incident as he did to the new kid. He is also willing to save others when needed.

His bitter contempt for seeing others fear him and others has even caused him to see things like friendship, materialism and retribution as a sign of threat, torture, manipulation, and selfishness, in a word, "evil" and seeing that you sometimes can't trust anyone, not even yourself; which is what he usually indicates to Sonic and his friends when confronted in battle.

Here's his old backstory:

History

Early Life

Before Ominous turned out the way he was now, he was born and raised in a horrible place called "Shallow Valley". It was a dark, depressing, sinful, and oppressive place where most, if not all, people were either apathetic, jerks, or corrupt beyond belief. Crime and bullies were free to roam and do however they pleased; plants and animals were either withered, fled away, or killed in the process; the sky was mostly, if not completely filled with dark sky; the guards and other authorities were either overworked, uncaring, or just as corrupt as at least most of everyone else; huts were either run-down, filthy, or nearly unsafe to live in, and most of everyone else who had a slither of hope or happiness left in them in this area either lost it overtime, were forced to move, or had it all taken from them by either crime, poverty, or even death.

As a child, Ominous was isolated. There was no one he could trust; his parents were neglectful when they weren't being verbally, morally, or physically abusive due to him being the reason for inadvertently ruining their lives by virtue of their financial debt and mostly poor state ever since his birth. There was no one to give him a reason to think he did deserve to be loved when they called him a burden, told him he'd ruined their lives and frequently called him horrible words like evil or heartless. At school, it was more of the same, with teachers who had no patience for the quiet, bruised child who sometimes missed classes, and bullies who sensed his insecurities and relentlessly teased him, taunted him, beat him up when they felt like it and no one was watching.

Ominous hated the people in his world for the way they treated him. He hated the cruelty, couldn't imagine how someone could hurt another person, even if that person deserved it (as he sometimes thought he must). Then, one fateful day, the leader of the bullies grabbed him by the arm as he exited the schoolhouse. Instead of beating him up, which he had expected, the bully dragged him over to where the rest of the bullies stood, gathered around another boy. Ominous had seen the boy that morning, but only in passing; he was new to the school.

The bully told Ominous that he had two choices: help them beat up the new kid, or take a beating in his place. Ominous couldn't believe his ears. It seemed like a nightmare, but he couldn't wake up. It was all too real. He felt sick to his stomach, but with dreamlike horror he saw himself stepping forward, taking a swing at the new kid, then another. Beyond the ringing in his ears, he could distantly hear the bullies laughing and jeering. As he walked away, there was blood on his hands, and most of it wasn't his.

The worst part of it was that for a terrible moment he had reveled in it, loved the power, gloried in the fact that he was not the victim, not this time. And for that, he hated himself, now as much as he hated the rest of the world, thus thinking that his parents were right about him being evil and heartless. Everyone could be evil, would be evil, given the chance, he was sure. The world was broken, broken, and –

Ominous would fix it.

He resolved that, then, with the blood of a boy whose name he didn't even know on his hands and bile in his stomach, resolved that he would wipe evil out of the world. It was the desperate promise of a betrayed child, but it was something solid for him to grasp onto in an existence made up entirely of cruelly treacherous ground. He would bind himself so he could do no evil, and he would find chains strong enough to bind the totality of being, one way or another. No one could know, because they would try to stop him, everyone wanted to do evil, but in the end – Ominous would fix it. Ominous would fix it, once and for all.

Ominous' New Powers

After that fateful day, he was reported throughout the area for what happened to the new kid and was seen as a criminal. He decided to go into hiding, leaving behind his abusive and neglectful family and built a new home in the forest as shelter. A lot of time passes and as an adult, he would think of what ways he could use to help him fix the world. One day when he was taking a nap, he heard a loud sound from outside and went out to investigate; It turned out to a small glowing orb. Confused as to where it came from, he picks it up and it starts to transform him into the dark and powerful morality/empathy manipulating being he is now.

After gaining his new powers, he decides to use them as a means to finally end all conflict and evil in his universe. After the gods saw this, they thought that he was going to use it for more nefarious purposes and decided to seal him into a frozen state at the Mystic Ruins to make sure that it didn't happen. After that, they gave him the name "Ominous" as a reminder of his seemingly heinous actions, as well as put him in legend to make sure no one ever tries to break the seal.

During his seal, he was forced to watch visions of people's conflicts and lives beyond the omniverse as punishment for his seemingly heinous attempts. After seeing all of everything's problems and conflicts, as well as thinking about all of the other horrible events that happened to him, he took a long thought about what just happened and decided that, since his new powers are limited to gods in his universe, he decided to make it his goal to increase his limits to beyond omniversal in order to save not just his universe, but many others as well.

Ominous' Release

After 10,000 years of ageless imprisonment and seeing depressing visions, Ominous was finally released from his seemingly eternal prison by an unfamiliar figure, at least in his eyes. An egg-shaped mad-scientist named Dr.Eggman and his two robotic henchmen named Orbot and Cubot, who wanted to release him after hearing legends about him created by the same gods that imprisoned him to use his powers for their own nefarious purposes.

He was brainwashed into doing Eggman's bidding.

This is what he looks like:
https://vignette.wikia.nocookie.net/sonicfanon/images/5/59/Ominous.png/revision/latest?cb=20190718044925