The following is a combination of comics canon, toon canon, and headcanon that I have cobbled together in order to give this incarnation of Slade a background that the toon, sadly, does not provide. This is in no way an "official version" of what transpired to make him the villain that he is. It's just my personal interpretation of events.
Beginnings
- Slade is born an only child, the son of a loving mother but a less than affectionate father. His early years are mostly normal, but after his mother dies while he's still young, his father (already harsh and unforgiving) turns abusive.
- A few years after his mother passes away, Slade's father re-marries when he's in his early teens. The relationship doesn't last long since he's abusive towards his new wife as well. She maintains contact with Slade, however, as they two became close.
- Two years into high school, Slade drops out shortly after his 16th birthday, lies about his age, and joins the military.
The Military Years
- Driven by dark memories of his home life and encouraged by his step-mother, Slade quickly becomes a rising star, throwing himself at whatever challenges come his way. It's during one of his first engagements that he meets Wintergreen, a longstanding friend, ally, and father figure.
- Several years in to his military career, Slade is transferred to a training camp for the elites. It is there that he meets his future instructor and wife, Adeline Kane. Impressed with this natural skills, Kane takes Slade under her wing and teaches him everything she knows about combat, tactics, and guerrilla warfare.
- Slade achieves the rank of Lieutenant Colonel and marries Adeline soon after his training is complete. A few years later, Grant Wilson is born.
The Experiment and After
- Catching wind of the military's desire to create an immunity to truth serums, Slade volunteers for the project. Unexpectedly, the experiment goes horribly wrong as the chemicals send Slade into a fit of uncontrollable rage. He is sedated and falls into a coma for weeks after initial test.
- Finally, Slade awakens and is discharged by the military hospital. His health fluctuates for about a year, as he experiences bouts of extreme strength and weakness. Frustrated and depressed, it's during that period that Joseph Wilson is conceived.
- Eventually, Slade's health stabilizes, his body finally settling at baseline human ability -- or so his doctors thought. In reality, he became a metahuman, a "super soldier" for lack of a better term. Preferring to keep it a secret, Slade told no one of his new-found abilities.
The Birth of a Mercenary
- About two years after the experiment, Slade receives news that Wintergreen has been sent on the equivalent of a suicide mission. When he is forbidden to go after him by the military, Slade takes matters into his own hands, hijacks a helicopter, and goes in to rescue him. He is successful and pulls Wintergreen out of a hopeless situation, masked and clad in a jungle garb -- a prototype of what was to come.
- Upon his return, Slade is promptly discharged from the military for insubordination. To make up for the lack of action, Slade takes up big game hunting and becomes well known for it. On the side, however, he uses it as a cover to take jobs as a mercenary. He tells no one except Wintergreen what he does, which costs him in the long run.
Tragedy Strikes
- While Slade is away on a job, his younger son Joseph is kidnapped from his home by a band of terrorists. Adeline calls him back, and when he arrives, he reveals the truth -- that he's a mercenary who was contracted to kill one of the kidnapper's leaders. When the two of them go to save Joseph, the kidnappers demand that Slade turn over the name of his employer. He refuses and attempts to save Joseph on his own. In the result fight, Joseph's throat is cut, and he is rendered permanently mute.
- A few days after Joseph is hospitalized, Adeline confronts Slade about what happened. Determining that her family would never be safe as long Slade lived and put his professional standing first. She attempted to kill him that night, and though he lived, Slade lost his right eye forever.
- Devastated by what his hubris caused, Slade is taken in by Wintergreen for a time. Once he sufficiently recovers from the gunshot wound, Slade promptly burns the mercenary uniform that caused so much trouble. Recognizing Addie's point, that his family and friends would never be safe with him, he contacts her and strikes a deal: Instead of going through the pains of a divorce, Slade asks her to help him fake his death and to quite literally erase him from off the face of the earth. She agrees, fabricating the circumstances of his death as well as purging his name from every database she can find. When it's done, she tells him in no uncertain terms that if she ever sees his face again, she'll kill him.
Becoming the Villain
- For about a year after all ties with friends and family are severed, Slade languishes in Africa, depressed and mostly uninterested with life itself. Throughout this difficult period, Wintergreen (his only remaining friend and confidant) stays with him, trying to console him and to get him back on his feet. Slowly, Slade comes out of his funk, until finally, one day, Wintergreen awakens one morning to find him gone.
- For the next five years, Slade takes the equivalent of a world tour, learning from the best. Finally making use of the intelligence he never bothered to exploit in school, Slade discovers fields of study he never considered before: biochemistry, robotics, ceremonial magic, and more. Increasingly fascinated with the dark world of criminality, Slade begins to change, molding himself to the shadowy world he's become so accustomed to. During this period, he meets Sweet Lili, a Cambodian princess. After he saves her from a dicey situation, the two have an affair. It's years later that Slade learns a daughter named Rose resulted from that union.
- Finally, Slade returns home, a changed man, but not necessarily for the better. He's more formal, cold in a way that's unsettling, and his hair is completely white. Dissatisfied with his estate in Africa, Slade moves back to the states, searching for a niche from which to operate with his newly acquired skills. Eventually, he settles in Jump City, and over the course of several years, he creates the dark persona he later becomes infamous for and engineers a massive criminal empire with contacts all over the world.
- Not too long after, the Teen Titans appear on the scene, and while he initially only takes a passing interest in them, as he considers the necessity of taking a successor, Slade begins to scrutinize them more closely, particularly Robin.
Thus, a long and convoluted history with the Titans begins...