The Birth of Deadpool:
I, Wade Winston Wilson, was born to my army general father and terminally ill mother. After my Mom's death from incurable cancer of the lungs, my Dad began to abuse me and turned to alcoholism. The influence of my violent Dad turned me into a typical teenage delinquent. Around age seventeen, my Dad was killed by one of my drunken friends in a bar fight and I soon dropped out of high school to enroll in the United States Army Special Forces. I was kicked out of the army after a short tenure and then turned to mercenary work, soon establishing a formidable reputation. Unbeknownst to me, around this period, the interdimensional law firm Landau, Luckman & Lake had discovered from their precognitive department that I was destined to play a significant role in a future golden age for humanity and started to monitor me via their agent, Zoe Culloden, a.k.a. the Expediter, while their principal precognitive, Montgomery, researched my whole life. During visits to Boston, I developed a relationship with then-runaway and prostitute and future fellow mercenary Vanessa Carlyle, later known as Copycat. However, I developed terminal cancer within the few following years and having, perhaps deliberately, botched a mission that was meant to end in the murder of my future prisoner/roommate Blind Al (although I killed every other individual at the army base in which she had been stationed, and Zoe intervened to protect Vanessa from a revenge attack by his former employers). I indifferently broke up with Vanessa, whose love I genuinely returned, in order to spare her the burden of my illness.
Dying and desperate for a cure, I volunteered for the second Weapon X program, where my body and mind were altered on a genetic level. The genetic manipulation was initially supposed to grant him a superhuman regenerative healing factor (based on the DNA of former Weapon X experiment Wolverine), stopping the progression of my cancer and greatly enhancing my physique. However, the cancer interacted with the genetic process in unanticipated ways; the process (initially) failed, disfiguring me horribly and making me significantly mentally unstable. I was initially assigned to a field team alongside Garrison Kane, Sluggo, and Terraerton a.k.a. Slayback, who were all deemed to be successful subjects at the time. Despite outwardly appearing as a man with a good background (a wife, children, and a home — all things that I lacked), Terraerton proved to be completely psychotic, and I killed him with explosives.
I quickly washed out of Weapon X and was sent to Doctor Killebrew's "Workshop" at The Hospice, a place for failed experiments, where I was tortured and experimented upon among other washouts. In the Workshop, I became part of a game called "the Dead Pool", where inmates bet on which one of them will die next. As I had been chosen as a "special project" by Dr. Killebrew, my odds of dying were very low, making me the leader of the Dead Pool with over one thousand-to-one odds. During near-fatal experiments, I started to see visions of Death and fell in love with her, while she became interested in me as it was unheard of for a mortal to perceive her ahead of death. I decided to break the Dead Pool by doing anything to get myself killed so I could be with Death, attempts which were repeatedly thwarted by my rival and Killebrew's enforcer, Ajax, then named The Attending. Showing no fear due to my desire for Death, I continually baited and played pranks on The Attending, taking particular delight in mocking his true name, Francis, who retaliated by sending me to Killebrew for further experiments. My erratic behavior inspired the other inmates of the Workshop to rebel; I was seen as a threat to the order in the Hospice but Dr. Killebrew refused to let anyone die or be killed, unless one inmate was to murder another. It is only after I killed my friend Worm out of mercy after The Attending intentionally lobotomized him in order to escalate the hostilities between them that Killebrew ordered his death as The Attending had expected. It is this attempted execution that finally activates my healing factor, much to the chagrin of myself and Death. The kick-start of the regenerative process accompanied by the culmination of my disfigurement (which should have theoretically reversed itself) and the accumulation of the various traumatic events I had undergone to this point caused me to finally snap completely. Because of the healing factor's emphatic prevention of my death, Death rejected me. I managed to escape, (temporarily) killing The Attending and freeing many other Workshop experiments, taking on the name "Deadpool" and returned to mercenary-for-hire work.
I only know this thanks to the various creators of my comic (Thank you 4th wall!).