Josh Foley first appears as a member of the Reavers, an anti-mutant group led by Donald Pierce. When Cerebro detects a mutant in the area, Danielle Moonstar and Karma investigate. The Reavers attack Moonstar's New Mutants squad, and one of Foley's allies is severely injured. Leaning down to aid his friend, Foley's mutant power manifests and he heals Laurie Collins.
Sent to Xavier's
Outed as a mutant, much to his own surprise, and rejected by his friends and family, Josh reluctantly joins the Xavier Institute and becomes Prodigy's roommate, a situation neither finds appealing. Unable to overcome their bigotry, Josh's parents sign legal guardianship over to Dani Moonstar. He is assigned to Dani's New Mutant squad who eventually reach out to him as he comes to accept his mutation.
Secret romance with Rahne Sinclair
Shortly afterwards, a depowered Rahne Sinclair visits the X-Mansion. Josh is instantly smitten by the new "wild child" Rahne, and sneaks out of the Institute at night to go to a bar where Rahne is playing pool. Josh realizes that her new attitude is a way of letting out instincts she had previously been able to blame on "the wolf." The two kiss, and Josh unconsciously heals Rahne's depowerment. The wolf takes over and she loses control, slashing Josh open. Fortunately, Laurie witnesses the attack and uses her pheromone powers to drive away Rahne. While Elixir is rushed to the mansion's infirmary, Beast reveals the full potential of Josh's power: he can manipulate all the body's functions on a genetic level, and the fact that Josh only heals is simply inexperience. Josh receives an I.V. drip, but with Archangel, the mansion's other healer, absent, there is little hope. However, Prodigy realizes that Josh can heal himself if only he were to wake, and Beast reluctantly follows Prodigy's plan. Surge wakes him with her powers, while Laurie keeps him calm so he can heal himself. As an unexpected side effect, Josh turns his skin and hair to a reflective gold color. Josh and Rahne continue to see each other secretly for a few months until Rahne witnesses him on a date with Laurie and ends the relationship. Josh is depressed at first, but eventually realizes that it was for the best and pursues a relationship with Laurie. However, Wither also has a crush on Laurie, and reveals Rahne's and Josh's previous relationship to the school. With the exception of Surge, most of the New Mutants team ostracize Elixir for his involvement with a teacher. Eventually, the New Mutants squad's in-fighting begins to affect their ability to act as a team. Concerned with the future of her team, Wind Dancer convinces everyone to get together for a camp-out so they can work through their issues with one another. The evening ends with Josh speaking candidly with Icarus about his disappointment over his own actions. The other members of the team overhear and he is reconciled with David and Laurie. Meanwhile, Josh heals Colossus and Shadowcat, after both are impaled through the lower torsos during an attack by the sentient Danger Room. The strain of this effort causes Josh to collapse.
Decimation and Childhood's End
The events of House of M leaves only 27 students with their powers, including Josh. Fearing their safety, Emma Frost orders the depowered students and staff, including Josh's guardian Danielle Moonstar, to leave the Institute. As the depowered students and staff leave, one bus of depowered students is bombed by anti-mutant zealot Reverend William Stryker, killing all on board. Josh is unable to heal them in time, and becomes severely depressed and loses confidence in his abilities. Most of the remaining students take part in a melee fight organized by Emma Frost to determine who will be members in the new group of mutant heroes in-training, the New X-Men. Despite his non-combat powers, Josh makes the team. During one of their first training sessions, the New X-Men spar with Colossus. Caught up in his emotions over the deceased students, Josh hits the powered-down Colossus over the head with a metal beam. Furious with his action, Emma temporarily kicks him off the team. Afterwards, Laurie and Josh argue about Josh's place on the New X-Men. Laurie explains that Emma is all wrong, that the team is merely about "violence and fighting," whereas Elixir can do a "beautiful thing". However, Josh tells Laurie that when he tried to heal DJ, "I could feel him dying...his life bleeding out of him," and that "when he died, he took a piece of me with him, a piece of me died, too". At that moment, Laurie is killed by a bullet fired by one of Stryker's agents. A distraught Josh remains with Laurie's body until they are found by several of the X-Men and students. When Wolverine attempts to restrain Josh from Laurie's body, Josh's power surges and causes painful boils and blisters to appear on Wolverine's hands and wrists. Stryker begins an attack on the institute but Josh sits unresponsively in the infirmary. Coming to his senses and enraged over the death of Laurie, Josh uses his power to kill Stryker. This act of revenge turns Josh's golden skin into metallic black and Josh falls to the floor, catatonic. According to David, Josh's killing of Stryker not only changed the color of his skin, but also altered his brain chemistry.
Nimrod and funerals
When X-23 is mortally wounded and unable to heal during the final battle with Nimrod, Hellion rushes her back to the Institute with help from Emma Frost, who unlocks the part of his brain which controls his powers. Julian gives a motivational speech and gets Josh to move forward with his life. Josh heals Laura, which also turns his skin back from black to gold. Shortly after it is discovered that a small part of black still remains on Josh's skin, moving from place to place. Josh states he could still kill but he will need to learn how to control his powers and use them only to heal. He, like the other remaining students and staff, attends at a memorial to remember all the students who were killed in Stryker's raid of the school.
Change of attitude
Since waking from his coma, Josh seems to have taken a more peaceful approach to life. In New X-Men #32, Rockslide states, "Since Foley's gone all zen, we'll probably need a replacement." In issue #33, Josh approaches Beast and asks him to teach him everything there is to know about human anatomy, physiology, and biology. Josh states in issue #32 that he always knew that he could do more, and though Anole suggests that Josh stop studying in lieu of having the Cuckoos simply placing Beast's knowledge into his brain, Josh states he would rather do it the right way. He has begun to wear only white clothing, and, when not studying, seems lost in thought and is introspective. Before the other students are teleported to Limbo, the Stepford Cuckoos help Elixir learn advanced science by taking information from the Beast's head and putting it into Josh's. This increases his power exponentially, allowing him to heal otherwise-fatal injures with a touch. He also masters his "black abilities" by being able to switch instantly from golden/healing to black/disease-causing. After Belasco rips out David's heart, Elixir rushes over and touches him. David begins growing a new heart out of nothing and comes back to life. Josh is exhausted after healing David and passes out. He demonstrates his darker abilities in the same issue, causing the demon that is holding him to swell up and bleed out of its ears, before having its entire head explode.
World War Hulk
Elixir is one of the students that goes up against the Hulk in World War Hulk: X-Men. He is carried towards the Hulk on Beast's back. Elixir touches the Hulk which affects his healing factor and gives an opening for the others to attack the Hulk. He and Beast are punched away by the Hulk, but Elixir heals Beast so they can try again. Once Hulk has defeated The New X-Men, Elixir and Beast are the last ones left. Hulk is about to crush them but the "Astonishing" team arrives and saves them.
Children of X-Men
When Mercury comes to ask Elixir about his age, he is sitting alone in the dark and tells her instead about his cells and how he feels them aging and dying freaking her out. When Surge interviews him about what happened to David in Limbo, he tells her nothing happened. Later when Kitty Pryde tries to have a student/teacher conference, he is still sitting alone in the dark. When she asks him what he is doing, he tells her he is thinking about life and death and how he can give it and take it. “With everything my powers can do… Really Miss Pryde… What can’t I do?” This scares her and she leaves quickly. Later in a faculty meeting, she thinks he might become the next Magneto. Still sitting in the dark, Elixir is thinking and his skin goes from gold to black. Loa comes to his room and asks if he wants to make out. His skin returns to gold and he says sure with a smile.
When some of the New X-Men decide to launch a preemptive strike against the Purifiers, Elixir sits out the fight because he is worried he will kill every single one of them. When the sentinels attack the mansion, Elixir and some of the students left behind are incapacitated. They remain unconscious in the infirmary during the conclusion of Messiah Complex, he is also seen in a hospital bed with Loa sitting by his side.
Josh, presumably recovered from the sentinel attack, was brought in to cure Wolfsbane after she was given a deliberate heroin overdose by the Purifiers. Upon healing Rahne, she attacked Josh, moving on to her real target, Angel, tearing out his wings and delivering them to Reverend Craig. Josh heals Angel's wounds, but his attempts to regrow his wings are thwarted by the discovery that Warren's wings were never really organic and that he still carries the Apocalypse techno-organic strain. Elixir and Loa are still together, which is revealed by X-23. Due to Elixir being a "problem" to X-Force, X-23 contacts the Stepford Cuckoos to help Rahne and erase Elixir's memories of the team, by Josh's request. However, before his memories can be erased, X-Force is interrupted and sent on a mission. Elixir joins X-Force and receives a dark-colored uniform. He helps his new team capture Vanisher, by creating a deadly brain tumor in his brain. Elixir doesn't take part in the battle with the Marauders' clones, and instead hides with Vanisher, who calls him "Mother Teresa," and tells him that he should join the fight and help his teammates. Elixir later keeps X-23 from killing herself after she becomes infected with the Legacy Virus, and helps her get rid of it. Elixir is transported to the future, along with the rest of X-Force, by Cyclops in order to bring Cable and the mutant child back to the present. Once they arrive there Elixir is in a hysterical state over being unable to save his friends from the Leper Queen. During his stay in the future he confronts Stryfe along with Wolverine and Proudstar, managing to infect him with cancer. However Stryfe telepathically forces Josh to heal him undoing most of the damage. After the battle with Stryfe he and the rest of X-Force say goodbye to Hope and Cable, with Josh claiming that he knows what she (Hope) is. He, Wolverine and Archangel get back to the U.N. in order to save Surge and Hellion. Josh cures them but falls into a coma as a result. He is later revived by the Norse goddess of death Hela upon Hrimhari's request so that he can save Wolfsbane and their child. Elixir heals her by transferring some of her baby's strength to her to ensure that she can survive the pregnancy. He and the X-Force team then head to Genosha. Elixir faces off against Wither in a fight to the death, Wither declaring he will kill Josh for failing to protect Laurie, that only Kevin himself could have saved her and he was the only one to love her. Elixir shifts to his black form, tells Kevin he always loved Laurie, then reverses Wither's effects, turning Kevin to dust. Wolverine later states that Elixir has quit the team, citing he is having difficulty shifting out of his black form.
Powers and Abilities
Elixir is an omega-class mutant, and an Omega Level Healer, with Omega-class healing ability. He was stated to be a General Threat by the O*N*E, at the time of the M-Day, but was orange-flagged and allegedly reclassified by the O*N*E after he used his powers offensively.
◾Biokinesis: Elixir is capable of controlling the biological structure of his own and other people's bodies. He can produce biomolecular energy at will to affect organic matter he touches. This allows him to heal physical damage done to his body or the bodies of others, reactivate suppressed mutant abilities, repair cerebral functions, and alter the composition of his own molecules in certain ways. Because of his control over his own biology, Elixir has proven to be very difficult to treat medically. He usually passes out after pushing his powers too far and remains in a coma for some time. Dr. Nemesis guessed that during these times, his DNA reboots itself. He is theoretically capable of rewriting someone's genetic structure at will, and may eventually develop enough control of his powers to manipulate the human genome, altering eye, hair and skin color, implanting physical characteristics or even reactivating dormant mutant or atavistic genes. He himself fears that he has only “scratched the surface” of what he can do. His ability is by close proximity - he tends to touch his targets, but can heal/kill through clothing. However, recently Josh learned to use his powers on several targets at the same time, without touching them. ◾ Healing: At first he was capable of basic healing, having successfully healed broken bones, severe burns and even a mortal stab through the chest. After gaining Beast’s knowledge of human anatomy, physiology and biology, Elixir has demonstrated increased mastery of his powers: regrowing Prodigy’s heart,  sedating an enraged Wolfsbane and cleansing her body of drugs, curing X-23 of the Legacy Virus, and even transferring vitality from one person to another, as he did with Wolfsbane and her unborn child. ◾ Resurrection: Elixir can bring people back from the dead.
◾ Death Touch: He can use his powers to harm others, to cause different types of illnesses, massive swellings and organ failure. He managed to kill Stryker just by touching him for a few seconds, causing deadly harm to the powerful demon Belasco, and almost instantly annihilating Wither’s body. His control over his abilities is now so refined that he was not only capable of giving the Vanisher a brain tumor, but even of shaping it into the X-Men logo.
Josh's Secondary Mutation ◾ Dichromatimorphic Skin: After Elixir used his mutant powers to heal himself, his skin turned a golden color. This is possibly due to Elixir activating a Secondary Mutation in himself. Elixir's skin normally remains golden, but if he uses his powers to damage or kill his skin turns a deep metallic black, and Prodigy theorized that it is also altered his brain chemistry.This appears to be a completely involuntary reaction, and it has been stated that Elixir has a hard time converting from black to golden.
Due to the psychic data transfer by the Stepford Cuckoos using the knowledge of Beast, Elixir now possesses genius-level understanding of human anatomy, physiology and biology. .
Due to the psychic knowledge taught to him by the Stepford Cuckoos using the knowledge of Beast, Elixir now possesses Genius-level understanding of human anatomy, physiology and biology.
Because of his control over his own biology, Elixir has proven to be very difficult to treat medically. He usually passes out after pushing his powers too far and remains in a coma for some time. Doctor Nemesis guessed that during these times, his DNA reboots itself.
Elixer's first case of activating suppressed powers was when he reactivated Wolfsbane's wolf powers when they kissed, which caused his gold skin when he recovered.
It is currently unknown if elixer's gold/black skin is the result of a secondary mutation or a side effect of his powers.