Diana meets up with him as Clark Kent. He had last seen her when she was just a normal human woman trained in the martial arts. (I-Ching era) Diana does not recall any of this. Clark has to remind her that she had lost her powers. Sensing something was wrong, he tells her to change into Wonder Woman and meet him at the JLA Headquarters.
Superman arrives at Headquarters and Diana is not there. Instinctively he knows where to find her. She is at the old JLA base and she appears confused and distraught. Superman comforts her and assures her that they will find out what's wrong with her.
Back at the JLA headquaters the League are trying to decide what to do about Diana. Batman cannot find anything wrong with her memory but it just seems she cannot recall the last few months. Diana is not happy with this explanation. She demands to know about this part of her life. Superman tries to reassure her than now she was back with the JLA that they would get to the bottom of the mystery. But does not think she deserves to be part of the team.
She insists she will rejoin only after she feels she is worthy. She will undergo twelve tasks. Much like the twelve labors of Hercules. She requests the JLA monitor her and if she succeeds she will rejoin.
The JLA nominates Superman as the first one to monitor Diana and at first he is not keen because he feels he can't be objective. It's clear Superman has softer feelings for Diana, just by the way deals with her. But the League feels he is professional enough not to let them cloud his judgement. He follows Diana as she visits Paradise Island and we find out that the Amazons had somehow been responsible for her lost memories and that Steve Trevor was dead. Vulnerable and grieving Diana encounters a villain called the Cavalier who tries to control her with his hypnotic powers. Before Superman could intervene, Diana demonstrates she does not need anyone rescuing her. She can look after herself. She is a superhero after all.
Superman's faith in Diana is rewarded and he is happy to report to his JLA allies that she passed her first trial.