Biography - page 7
Simon's soul passed on into the afterlife, but his body was still as "alive" as it 
had ever been, merely dispersed beyond its ability to reassemble. This left Simon with a foothold in the world of the living, one maintained by the strong emotional connection he still felt to the Scarlet Witch. The time came when Wanda was in serious trouble, her hex power used as a conduit for the Celtic magicks of Morgan le Fay connecting to the Asgardian Twilight Sword, giving the sorceress the power to remake reality as she wished and enslave the Avengers as her private army, the Queen's Vengeance. The only being unaffected by the spell (because she was part of it), Wanda was imprisoned by Morgan and continually called for help, bolstered by her hex power and magicks. Her "call" unknowingly interacted with Simon's emotional tether, providing the final push he needed to reconsolidate his ions into a physical form, freeing Wanda from Morgan's dungeon. [Avengers (3rd series) #2]
On the run from Morgan, Simon and Wanda had an awkward reunion. He never openly admitted his love for her was what kept him from fully crossing over, but Wanda was smart enough to guess. After Simon faded from existence following his initial manifestation, Wanda recognized it 
was her need for him that caused Wonder Man to appear. Sure enough, Wanda gathered before the Avengers, freeing them from Morgan's control as she summoned Wonder Man to fight on her behalf. Wanda channeled the full power and faith of the entire Avengers roster into Simon, causing him to explode again and take Morgan's power with him, restoring reality to its true state. [Avengers (3rd series) #3]
In the weeks that followed, Wanda discovered she could manifest Simon at will, summoning him in times of need to bridge the gap between the living and the dead. [Avengers (3rd series) #5-7] The ramifications weighed on her, though, and Wanda eventually refused Cap's order to summon Simon in a combat situation, sick of using him like a weapon instead of a person. That night, 
Wanda was troubled and questioning her role on the Avengers team at all, when Simon manifested in response to her subconscious needs to console her. Despite her surprise at his abrupt appearance, Wanda welcomed Simon's consolation, and they spent the night together. [Avengers (3rd series) #8] Wonder Man's connection to the world of the living was clearly growing stronger, as the next day he materialized in defense of Wanda against Moses Magnum after Wanda had already been rendered unconscious. [Avengers (3rd series) #9]
Unfortunately for the Avengers, Simon wasn't the only Williams brother in the realm of the dead looking to return. The Grim Reaper used his supernatural contacts to monitor the connection between Simon and Wanda, and found a way to exploit it. Manifesting in Central Park during the "Avengers Day" parades, the Reaper channeled the macabre forces at his command to resurrect the essences of seven dead Avengers as the new Legion of the Unliving, including Simon. 
Possessed by the Reaper’s own sense of despair, the undead Avengers were zombie-like and malevolent, overpowering their living counterparts as Grim Reaper lay claim to the world of the living to bring Hell to Earth. By feeding on the despair of the onlookers, the Reaper created a mystical force-wall in Central Park that contained a pocket of the Hell dimension he now inhabited. The more despair he absorbed from others, the larger the force-wall and the Hell inside would grow.
Wanda had been absent from the "Avengers Day" festivities, but she was captured by Wonder Man and the Legion when she returned to the Mansion. Simon was caught up in Eric's hatred, claiming the Reaper was responsible for his returns, all along while blaming Wanda and the Avengers for letting him die in the first place. Wanda had just returned from communing with her mentor Agatha Harkness, however, and had a greater understanding of her powers than before. With concentration, she freed Simon and the Legion from the Reaper's control and sent them to free the living Avengers from Central Hell. To end the Reaper's threat, Agatha Harkness counseled Wanda on how Simon's love for her was the magic that anchored him to the world of the living. To bring him back fully, all she needed to do was return that love. Wanda overcame her reservations about loving freely again after the Vision, allowing her to fully pull Simon back to life.
Simon wasn't willing to leave it at that, though. His love for his brother Eric still connected them across the boundaries of life and death. Eric still loved him back and had become the Grim 
Reaper in the first place out of love for Simon, but all the complications and setbacks since then had twisted Eric's love with despair and jealousy. Wonder Man reached back through the void of Hell and pulled his brother from it. By making Eric reject his despair and admit he still loved Simon back, the two of them connected as Simon connected to Wanda, and Eric Williams became alive again as well. [Avengers (3rd series) #10-11]
Back in the land of the living, Simon was happy to reunite with his best friend, Beast, and his brother, Vision. He was a recognized hero, living in a mansion and with the woman he loved finally loving him back. There was some hesitation in their relationship at first, for Simon's "brother" Vision had regained his emotional drive in recent months, but Vision gave Simon and Wanda his blessing while claiming to be a "different person" now than he was before his deconstruction. [Avengers (3rd series) #12] Despite all his success (or perhaps because of it), Simon felt uncertain about his future. He remembered the mania that consumed him during his power fluctuations before his death, and painfully recalled his attacks on the Avengers and at least two 
deaths because of his actions. Simon wasn't completely willing to accept the judge's post-mortem ruling that he wasn't responsible for those actions, feeling it might have been taken more seriously if he were still alive at the time to answer the charges. Because of these feelings, Wonder Man remained an in-house associate of the Avengers only, officially Wanda's guest at the residence instead of functioning as an active member of the team (although he still accompanied them on most missions). [Avengers (3rd series) #14-15]
Wonder Man visited his brother Eric regularly in prison, and was distressed to learn Eric disappeared from the facility after an attack by unidentified robots. [Avengers (3rd series) #0] He soon learned the robots served Ultron, who also captured him, Wanda, Vision and several other Avengers. Ultron intended to extrapolate from their brain wave patterns (much as he once did to create Vision from Simon's) in order to create endless variations of new personalities for his artificial "children." When Vision attempted to reason with Ultron, he revealed his own sense of loneliness and isolation from humanity and let slip he still was in love with the Scarlet Witch. [Avengers (3rd series) #19-22]
After the battle with Ultron, Simon and Wanda attempted to speak to Vision and reach an understanding with him about their relationship. Vision continued to say he wished Wanda well in her new relationship, but instead turned his anger towards Simon. Simon didn't understand, so Vision began pointing out their various similar interests. Initially, Simon thought it was great to have a brother he shared so much with, after being so different from Eric growing up. His mirth at 
the idea ended once Vision screamed "YOU DON'T UNDERSTAND!" and punched him through a wall hard enough that it shook the entire mansion. The Vision fled the mansion after that exchange, and Wonder Man followed. After another brief confrontation, Vision admitted he had sunk back into the same feelings of inadequacy he developed when Wonder Man was first resurrected years ago. Simon and Wanda's shared love only reinforced the idea in Vision's head that he was nothing more than an inferior copy of Simon Williams, with no identity or feelings of his own.
So Vision was understandably shocked when Wonder Man confessed how much he had always envied Vision.
In Wonder Man's mind, Vision got to "be" Simon Williams without all the baggage, the weight of all the mistakes Simon had made in his life, from embezzlement, to Zemo, to Armed Response. The 
Vision was a Simon Williams free of these bad choices, while Wonder Man had to live with them. And despite the fact that he had been forgiven for all those poor decisions, or perhaps because of it, Simon still felt inadequate and unworthy of Wanda's love and the general heroism people ascribed to him every day. Emotionally reeling from learning Simon's perspective, Vision flew off into the night to think on his future, and Simon returned to the mansion, feeling he had driven his brother away, with one more thing to feel guilty about. [Avengers (3rd series) #23]
Still concerned over his past actions and even more shamed after his falling out with the Vision, Wonder Man felt the need to leave the Avengers for a while. He wasn't ready to officially join the roster again, yet wasn't dealing with the unresolved issues of his life (and death) while living in the mansion and effectively on-call for missions anyway. When a roster shake-up changed the team around, Simon accepted a spot as an active reservist and promised Wanda he would return as soon as he was ready. [Avengers (3rd series) #27]