In desperation, abandoned the woman he loved to try an obscure treatment in London.
Turned out the treatment was a sham run by a group of scientists messing with shit they didn't understand and mutant genes.
"THE GUY WAS AS GOOD AS DEAD WHEN HE WALKED IN."
"NO, YOU GAVE UP ON HIM AND CAST HIM OUT. BUT HE PICKED HIMSELF UP, AND WALKED RIGHT INTO THE SUNSET."
"WELL, YOU HAVE A DIFFERENT DEFINITION OF WHAT HAPPILY EVER AFTER IS... BUT YEAH, THE GUY WITH THE CANCER WENT OUT WITH THE TRASH. WHAT WE ACCOMPLISHED WITH HIS BODY MIGHT HAVE BEEN SPECIAL, BUT HIS MIND WAS GARBAGE."
The torture and pain inflicted on him caused him to lose most of his mind, a lot of memories, and any possible shreds of faith in humanity.
It also gave him a healing factor that fascinated the scientists in the program.
Of course, this ended in him escaping and slaughtering everyone that had to do with the program.
Oddly, the family of Wade and Mercedes Wilson were slaughtered the same day the RMS Titanic set sail.
Even stranger, Wade Wilson seemed to be aboard first class, claiming to be headed to America to visit his wife. Who is to question money, after all?
Can't remember why he is so desperate to go to America, just that something in his gut is telling him to go.
Still breaks the fourthwall, but that's just because he's lost a few too many marbles, right? He's just talking nonsense, that's the only explanation.
Seems far too cagey and anxious when people pay attention to him longer than he thinks they should.
Doesn't act like any typical high class gentleman with far too much money.
Despite being First Class, he seems to dislike his peers more than the classes below him.