Jean Loring began her career working as an attorney in Ivy Town around the same time as her then boyfriend, Ray Palmer, had become the Atom. Specialising in criminal law, the Atom would regularly assist Jean in cases before she discovered that Ray and the Atom were the same person.
Like with many girlfriends, wives or partners to super heroes, she would share in the dangers of their super powered loved ones regardless to whether or not they wished to. The first of many incidents saw Jean abducted by the sub-atomic Jimberen race. Although she was saved by the Atom and Hawkman, the treatment and ordeal had her driven insane and would remain so until she was eventually "cured" by the equally insane alien, Jest-Master...albeit only for a period of time until the events of Identity Crisis.
Jean and the Atom shared numerous adventures together before finally getting married. There was happiness during this time, but soon the strain of Ray's double life as a super-hero and devotion to the Justice League of America an as a scientist became too much for Jean. While at their home Ray caught Jean and a man named Paul Hoben kissing in her car. Upset Ray leaves her to clear his head and finds a White Dwarf Star in Brazil.
While in Brazil due to an accident Ray was belied to have been killed. This incident pushed Jean back into the arms of Paul and after their affair Jean realizes that Ray must still be alive and goes to Brazil to find him. Meanwhile Ray has an adventure with the miniature tribe known as the Morlaidhian. While their Ray as the Atom falls for the Princess Laethwen and has an adulteress affair of his own. When he comes back he and Jean are unable to reconcile their lives with one another, the couple divorced.
Eventually Ray moves out of Ivy Town to live with the Morlaidhian. Jean began a new life for herself as well and soon was remarried to fellow attorney, Paul Hoben with whom she had her affair. Furthermore she re-located with her new husband to where she opened up a small firm. For several years they worked together, but soon Jean would return to Ivy Town and on her own. Returning to Ivy Town, she became a senior partner at Grabemann, Loring & Ross.
In the events of Identity Crisis Jean suffers a mental breakdown, to what can be argued was a relapse to the ordeal she faced with the Jimberen race. Desperate to be reunited with her former husband, Ray Palmer, Jean concocted a plan to gain his attention and regain his affections once more.
Using one of Palmer’s old Atom costumes, she shrunk herself and entered Sue Dibny with the intention of giving her a minor stroke. Sadly it was too much for Sue Dibny and it resulted in her death. In an attempt to cover up her actions, Jean incinerated the body and faked an attempt on her own life. Shortly after Sue's murder, Jean pretends to hang herself. These events cause the superhero community to go after every criminal and villain they've ever faced, which results in the death of Firestorm. In the midst of all this Jean sends a gun and a "Protect Yourself" note to Jack Drake, Tim Drake's father. She hires Captain Boomerang to kill Jack Drake. This causes a chain of events in which Jack shoots Boomerang just as he throws a boomerang right into Drake's chest. The weapons hit the men at the same time and they both die instantly. Her deceit did eventually bring Ray Palmer back into her life, but after revealing information about the murders, Palmer was able to deduce his former wife’s involvement.
It was apparent that her mental health was no longer in tact and Jean was finally put away at Arkham Asylum for the murder of Sue Dibny. There she would come across a shard of “ The Heart of Darkness. After being repeatedly raped by the guards, the black diamond entices enraged hosts into allowing the entity known as Eclipso to possess them.
While possessed by the Eclipso entity, she is able to seduce the Spectre and manipulate him into destroying all magical beings. Eclipso’s influence over the Spectre was complete and they almost succeeded but were ultimately thwarted by the Shadowpact intervention along with Captain Marvel and the wizard Shazam himself. Eclipso and the Spectre’s rampage caused utter destruction to the Rock of Eternity and ended up killing Shazam. The Presence’s attention was finally drawn to the Spectre, stopping his rampage by forcing it into a human host. As for Eclipso, she was sent orbiting around the Sun nullifying her power.
In an attempt to resurrect his deceased wife, Ralph Dibny, the Elongated Man, enters a pact with the Spectre. The Spectre (once again without a host due to allowing Crispus a year to be himself before he became his new host) would resurrect Ralph’s wife if he would punish Eclipso. Endowing Ralph with his power takes Eclipso back in time to the point where she murdered Sue Dibny, trapping her in an eternal time loop forcing her to watch her murdering his wife over and over again. During this time, Jean’s sanity had been restored . Scared and in tears she begs for forgiveness, saying that she loved Sue and would never have killed her had she not lost her sanity. Affected by her pleas, Ralph was still human enough to feel pity and ended his pact with the Spectre, returning Jean and the Eclipso entity to her orbit around the Sun.
After a time, Eclipso wrestles free away from the Sun and returns to Earth. After failing to obtain a new host, she corrupts Mary Marvel who joins Eclipso in corrupting other super heroes. It is soon ended when Mary Marvel, refusing to becoming one of Darkseid’s concubines, rebels and battles with Eclipso. Mary Marvel would prove too strong, after calling down the magic lightning bolt, she is able to remove Eclipso's power from Jean, who falls into the ocean. Abandoned by the Eclipso entity she is seen sinking into the ocean’s depths.
It is confirmed that after the events of Countdown, Jean Loring had died. She is one of many deceased re-animated by Black Hand, avatar to the Black Lantern Corps. Jean is shown ripping out Damage's heart, essentially killing him. Damage's death would be the final victim that would allow Nekron's resurrection. While further chaos ensues with Nekron rising, Jean takes this opportunity to shrink herself, Ray Palmer and Mera into the newly re-animated Damage's Black Lantern Ring.