Although he continued to struggle with fear of death and failure, he largely overcame fear of death with emotional support from Hank Pym and the Vision.
He confessed feelings of inferiority to the Vision, who he began to regard affectionately as a twin brother of sorts.
He would occasionally return to the Avengers to help them on an as-needed basis.
Simon was among the Avengers who founded their West Coast branch.
Afterwards, the Avengers accepted Wonder Man as a staunch ally and he was later elected to full-time membership.
His presence was always a source of tension for the Vision, who felt insecure as Simon was the source of his “life.” At one point, Wonder Man and the Vision were placed on "trial" by the Grim Reaper to determine which of them was the "real" Simon Williams.
In fact, Simon had really fell into a death-like coma.
Before he was buried, his brain patterns were recorded for scientific purposes (and were later used to build the android Vision.) Simon's body was about to be buried when it was captured by his brother, now known as the Grim Reaper and who had already battled the Avengers, blaming them for Simon's death.
The Scarlet Witch, the Vision's wife at the time, became bitterly estranged from Simon for his refusal, which actually stemmed from the fact that he held a long-time infatuation with her, and unconsciously wanted the Scarlet Witch for himself.
He finally agreed to allow the duplication of his brain patterns after a distraught Scarlet Witch suffered a mental breakdown, but the Vision declined the offer since he had realized that duplicating Simon's brain patterns would not truly, fully restore his lost personality, but merely create a similar facsimile.
On a later adventure, Simon joined with the Avengers to stop the alien races of Kree and Shi'ar from dragging Earth into their war.
The Shi'ar developed a massive "Nega-Bomb" to decimate the Kree empire, and Simon and the Vision tried to stop it. Simon found his powers mutating, eroding his mental and physical stability (for instance, he later found that his strength fluctuated with his emotional state, increasing when he became angry.) He radiated so much ionic energy that he began altering those around him.
Eric suggested that Simon embezzle money to invest in Eric's own business, which happened to be illegal racketeering with Maggia ties.