A dying Otto Octavius aka Dr Octopus, swapped bodies with Peter Parker aka Spider-Man, leaving Peter's mind to die with Octavius' body.
Assuming Peter's body, and retaining all his own and Peter's memories, he discovered that his much highly regarded foe, who he has never successfully defeated was a loser in real life!
He was disgusted that a man he respected, who had everything going for him, good looks, a gorgeous wife, genius intellect, superhuman powers as well as being a part of the Avengers, somehow Peter could never get his life together!
Otto decides to become superior than his nemesis, becoming a superior superhero, a superior husband, a superior scientist.
Here is my take on the Superior Spider-Man