When mercenary extrordinaire and eater of doughnuts Wade Wilson contracted cancer he went a little nuts. He signed on for Canada (the greatest country on the f*&$ing planet)'s Weapon-X program he was given an experimental treatment menu to imitate Wolverine's healing factor. He was cured of cancer but he could not become the hero that Weapon-X was supposed to make him. So he was sent to a secret facility for hero factory wash-outs. Wanting only to die and rid himself of the pain he gained a good friend namely a cyborg named Worm. When he encountered the being named Death, who he found to be the best reason to die, he tried more furiously to end his life. His plan: mock the much stronger, much faster much more twisted supervisor of the wash-outs known as The Attending or as Wade often mocked him with his real name: Francis. In the end his mocking wasn't what killed him. Worm was lobotomized for Wilson's actions who had quickly broken his friends neck so as to give him peace. Finally finding a reason to kill Wade he took the chance and ripped out his heart but because of his healing factor, the hatred for francis and a thirst for vengeance he was not allowed to die. Charging out to meet Francis he shoved two automatic rifles taken from some guards who now could --ahem-- look the other way about all this, into The Attending's gut and splattered his spleen. Proclaiming that Wade Wilson was now dead he then became Deadpool though it did cost him what was left of his sanity.
After a life of murder, maiming, mayhem and pretty much anything for money (pretty much) Deadpool's own disgust for himself lead him to try to turn his life around and become a hero. Life hasn't let him achieve this goal. He's been nailed by the last person in the world he would go for (Typhoid Mary), beaten into a bleeding pulp (by T-Ray) And beat up his closest friends (Al and Weasel). But Zoe Culloden, aka The Expediter, an agent of LL&L recently informed Deadpool of his role in the mysterious Mithras Directive in which she has been grooming him to be the "New Messiah". This idea if nothing else has really pushed 'Pool to correct his past transgressions. He has recently freed his long time room mate/prisoner Blind Al who despite years of torment from the Dead-man refuses to leave him having faith in him and perhaps some unpaid debt she owes.
The Merc with a Mouth, Wade Wilson’s greatest ability besides his healing factor is his ability to drive his opponents insane with his endless chatter. Deadpool was a volunteer for the same Weapon X project that created Wolverine. Although he sometimes attempts to be an “anti-hero” by accepting jobs only against “bad guys,” Deadpool’s frequent clashes with Cable (as well as his alliances with Cable) make Wade’s true nature somewhat murky. Wade also has augmented strength, agility, endurance and reflexes
Wade Wilson's first job after landing on Gaia, a world that seemed almost exactly like his own in some regards, was to work for Doctor Doom. Doom offered to pay, excessivly mind you, so long as he got data on Cerebro. He did so, but was stopped when a Cable of the Gaian world stopped him. It took several exchanges, but eventually Deadpool decided that working for Doom was unwise. Thus the data for Cerebro remains under his rug in his Gaian estate.
After that, his appartment ran away. Yep.
So with no place to live, Deadpool bounced from city to city, threatening anyone with children. Doing so introduced him to a girl named Kaos, a traveller of worlds and dimensions. She offered him amusement by taking him to various worlds, and also providing him with places to live on occasion. She is the only person Deadpool hasn't tried to outright kill at least once on Gaia. But he does enjoy shooting her.
Others that Deadpool became familiar with were beings such as the Scarlet Witch, Winter Soldier, and A large cat that was never seen again. He's always bursting through someone's window to add excitement. It can be anyones window he wants. Even the impossible windows... like windows in a basement.