Origin

Ray Palmer, one of the most brillant scientifics of the DC Universe found an object from space that would be known as a fragment of a white dwarf star. After examinating it and studying it he figured out that with just a little manipulation he would be able to change at will his own size and mass. It was thanks to this discovery that he became the second man to have the codename "Atom".

Justice League

Some time after becoming the new Atom, Ray Palmer would be offered membership in the Justice League of America, an offert that he would gladly accept. It was here where he developed a great friendship with his teamate Hawkman.

Getting married

While stiil an active member of the Justice League of America, Ray Palmer (Atom) met Jean Loring with who he would start dating and after that getting married. Jean Loring learned that Ray Palmer was the Atom after he revealed his super-identity to her.

No marriage lasts forever

Soon, Atom's super-heroic alter-ego took a toll on his marriage. Jean drifted into an affair out of loneliness. At this time, Atom discovered a subatomic world in the Amazon. He divorced his wife Jean and lived in this subatomic world for a time. Soon enough, Ray missed his old world and returned to it.

The suicide squad and back to the league

After returning to the normal world Ray Palmer would assist the Suicide Squad in a few mission, which helped the team overcome missions that would have failed otherwise.

However soon after that Ray Palmer would be invinted to rejoin the Justice League of America, an offer that he would gladly accept and was now in the team where he thought he belonged.

Zero Hour

During the crisis of time known as Zero Hour started by Hal Jordan as Parallax and the former member of the Teen Titans Extant (former Hawk) the two villains made a lot of changes to the DC Universe continuity and to the heroes themselves, while some were erased others were really...changed. One of the victims was Ray Palmer who was de-aged from a man that had 30 years old to someone in the body of a 17 years old teenager, however this didn't make Ray forget his past as an adult and a member of the Justice League of America.

Teen Titans

After beeing de-aged Ray Palmer would return to the Ivy University, where he used to work as the Physics professor in an attempt to return to his true age, however before he could do that he met Isaiah Crockett (Joto/Hotspot) a teenager who was a real genius and that would infront of Palmer manifest his powers based on heat for the first time, this led to both of them beeing teleported into one of the H'San Natall ships.

It was here were Ray Palmer would meet the rest of the teenagers who had just manifested their powers and that would become the newest incarnation of the Teen Titans.

Working with the new "superheroes" Ray Palmer was able to rescue Prysm who was in a virtual reality simulator program from the H'San Natall. After rescuing Prysm all of them were able to escape from the H'San Natall and return to Earth where they would meet the former ally of the Teen Titans Loren Jupiter (Mr. Jupiter) along with his daughter (altough they didn't know she was his daughter) Omen aka Lilith Clay.

After this unexpected and not planned mission Ray Palmer along with the rest of the new superheroes decided to stay together as a group and become the newest incarnation of the Teen Titans who would have the funding of Loren Jupiter (Mr. Jupiter).

Altough at first he didn't want to become a member, Ray Palmer would decide to join the Teen Titans while trying to discover a way to return to his real age, he became the leader of the Teen Titans. However he wasn't that happy about beeing the leader of the Teen Titans because he had been in the Justice League of America and considered that becoming a member of the Teen Titans after beein in the league, even when he was their leader was a step down for him.

Everyone has to grow up

Some time after this Ray Palmer would start to rapidly age because of some shifts in the chronal energy. It was also revealed that Waverider had taken one part of Ray's DNA during Zero Hour in an attempt to find a cure to what had happened to Ray during the time crisis. Thanks to this Ray Palmer became 30 years old man again, some time after this the Teen Titans disbanded after saving their teamate Joto (Hotspot) who had been thought dead.

Identity Crisis, 52, etc.

After Ray's ex-wife, Jean Loring, murdered Sue Dibny in the hopes of getting Ray to be concerned for her safety, she lost her mind. Jean was taken to Arkham Asylum but was soon liberated by the Eclipso entity. Ray was so distraught over Sue's death that he needed to run away, out of his world.

After shrinking away from his world, he came across a being that informed him of the multiverse. He eventually found a way to travel between worlds on a quantum level. He looked for himself on each world hoping to see a Ray that hadn't suffered as he had. On this world (Earth 51) he found himself working on opening a gateway to alternate realities. He then saw himself die in an explosion when the experiment went wrong.

Ray was scientifically curious what "he" was working on. He now had a reason to stay on this world when he discovered that the research his other self was doing had catastrophic consequences if they weren't completed. He also discovered that this Ray had a blind date set up with Jean. He jumped into this world and tried to figure out what event caused this one to be so different than his own.

Ray was living a "perfect" life until he was found by Donna Troy, Kyle Rayner, Jason Todd and The Monitor, who had been searching for Ray. The Monitor tells everyone that it is his job to become aware of and eliminate multiversal anomalies. Since Ray is not of this world, he tells him he must be eliminated.

Powers

Can alter size at will, and can alter body mass to deliver sizeable blows at a diminutive size. Since he retains his full strength, by rapidly mass-shifting he can leap like a flea. He can also become weightless to glide on breezes. By shrinking to the size of a subatomic particle he can travel through conductive landline wires at lightspeed. As stated above, he can travel across dimensional barriers.