Genis-Vell was a superhero-turned-supervillain from the Captain Marvel franchise - published under Marvel comics.
Genis-Vell was the cloned son of Captain Marvel and Elysius. His growth was accelerated and false memories implanted so he would be old enough and mature enough to face his enemies quickly. He was made to believe that he was the son of Starfox.
He was given the Nega-Bands of his father and took the name "Legacy," and he voluntarily chose the power, although slightly forced when he and his mother were attacked. It was some time before he gained true understanding of what it meant to be a hero.
At first he abused his power, using it to intimidate others and take revenge on people that had bullied him in the past. The Silver Surfer intervened and taught him a valuable lesson in the abuse of power. He was set straight after this. He was still far from being his father after this thought and dwelled on seeking revenge against Nitro for causing his father's death. Against his mother's wishes, he sought out Nitro where he found him on Hala. Legacy was able to defeat his foe but was unable to kill him, remembering his fathers words: "Defeat Your Enemy, Do Not Become Your Enemy". He brought Nitro back to Titan for imprisonment.
On Titan, he was met by Jack of Hearts who was seeking assistance in rescuing Ganymede from Thanos and Terrax. Although still inexperienced, Legacy agrees to help and they soon found themselves locked in battle with Tyrant. They proved to be no match for Tyrant even with the assistance of Ganymede and Terrax. When Thanos engaged Tyrant, Legacy and Terrax rescued the others and escaped.
As Legacy, he was able to quickly get to know his powers but still had trouble with the act of being a hero. He had no father, so he sought out the Silver Surfer once more for some advice. He was directed to the Surfer by a call through his ESP senses from the Surfer, but when he arrived the Surfer was dead. He used all the power he could muster and was able to revive the Surfer and restore his power and life.
He began calling himself "Captain Marvel," which put him in conflict with Monica Rambeau ( Photon) but this was resolved when she decided to take the name "Photon."
In order to save the life of Rick Jones, he bonded with him at the molecular level using the Nega-bands very much in the same manner that is father before him had. Thus he and Rick would split time between Earth and what they thought was the Negative Zone. That was until an encounter with Drax that revealed to them that they were actually traveling to the planet of K'ia, the home planet of Hulk's deceased lover Jarella, in the Microverse. During that same encounter he meets Visalia, a woman that claims to be Jarella's sister and she mistakes Drax for Hulk because of his appearance and diminished intellect. Drax, believing that he is Hulk, fights Marv and the Micronauts, he is stopped and Visalia is exposed as a fake. This bond also caused his cosmic awareness to awaken and in order to prevent him from going insane Moondragon placed psychic barriers in his mind to limit his new power and prevent him from going insane. They were always in constant contact with each other and when they spoke to each other they would see a giant floating head. Rick gave him the nickname Marv during their mental conversations. During one of their first adventures together they encountered a young girl who was losing control of her nigh-omnipotent abilities, the Skrulls wanted to use her as a weapon and the Silver Surfer wanted to kill her because she had the power to destroy the universe. Rick was able to save her by telling her to use her powers to alter the time stream so she would never get the powers.
During Maximum Security Marv meets the vengeful children of a man that his father killed, Zey-Rogg and Una Rogg. Zey is killed but Una is kidnapped by the Kree bloodhounds so she can be taken back to the home world to be "fixed". Marlo and Moondragon try to convince him to fly to the Kree home world and rescue her but he refuses because she tried to kill him. After receiving word from the Micronauts that Drax was acting irrationally Marv went to try and help him and found out that Psycho Man was controlling him to free Marv's evil future clone from an alternate dimension, Fredd. Fredd easily defeated Marv and used him as an experiment for a device that will take out of the Microverse, it backfires and Marv uses the machine to drive Fredd insane and he blows himself up.
When the alien death god Walker starts trying to kill Death, Thanos reveals that Marlo has been her host body since she was restored to life by Leader. In order to protect her Marv, Thor, Thanos, and Marlo travel to purgatory but Walker follows them. Since it is impossible to die in purgatory he forces Marv to switch places with Rick, blows off his arm, and ages him nearly 100 years. An angry Death takes over Marlo and tears all of Walker's power away from him. Rick's accelerated aging is transferred through the Nega-Bands and it begins to affect Marv's mind knocking him unconscious, he is mentally sent into the far future and he is at the grave of Songbird, on the grave it says that they were married and had two kids. Marv thinks that he is dreaming and he is attacked by a shadowed figure that blames him for Songbird's death. His mind then starts traveling back in time but stopping at various points in his life, he stops at the time when Songbird is giving birth to their second child and he is shocked to see his mother returned to life and before she can tell him how it happened his mind jumps again to a battle between himself and Magus. His last stop is during a time when he and Rick are both in the Microverse and Rick is yelling at him over his messed up life. Marv's mind returns to the present and he regains consciousness in the Microverse. Upon return to earth Rick becomes extremely depressed and tries to kill himself. Meanwhile Marlo's comic shop is in financial trouble due to a new competitor that is being run by the magician Maha Yogi. Yogi built the store so that he could gather enough sacrifices to summon the demon Grendel's Mother. Unfortunately for Yogi Grendel's Mother doesn't want to help him and she leaves him to fight Marv and Moondragon by himself. The fight is about even until Rick uses his vast knowledge of cliche ways to defeat a villain helps them deflect a spell back at Yogi destroying him.
In order to find a way to return Rick to his actual age Marv travels to the Kree home world to ask the Supreme Intelligence for help. He is defeated by Ronan the Accuser when he arrives and he is placed in a cell with Una Rogg. He frees them from their cell and confronts the Supreme Intelligence. He agrees to help Rick if Marv travels in to the Negative Zone and brings back a rare type of radiation, but the radiation only comes from a sun under the watch of Blastaar's son Burstaar. Una is able to manipulate Burstaar into turning against his father and they get the radiation. When they return the Supreme Intelligence tries to fix Rick but he fails and he is truly shocked at his failure. A short time after this Rick returns to his normal age and Marv believes that it was a delayed reaction to the process.
Marv had Moondragon remove the blocks on his Cosmic Awareness and over many months of meditation attempted to develop it. He now saw every crisis in the universe happening every second and had to make a choice of which to attend to, and after he made his decision he saw every possible outcome of what could have happened had he chosen differently. But this ability eventually drove him mad after he chose to save an entire race of peaceful aliens from being slaughtered over saving one woman murdered by her boyfriend. Immediately after she was killed he was shown her future as the universe's greatest peacemaker and that under her there would have been galactic peace for generations. He becomes desensitized to the problems of the universe and strands Rick in the Microverse for months while he goes out and tries to find a way to take over the universe. He conquers a warrior alien race with the slightest effort and it puts him in conflict with the Kree, among the Kree soldiers is his father's mentor whom Marv proceeds to kill in cold blood. He takes his armor and offers to join the army as his replacement.
As a member of the Kree army he shows no respect for his superiors but they are afraid of his power and can do nothing to stop him, he even charms his commanding officer's mistress and impregnates her. After returning from a mission killing a Shi'ar fleet he finds out that the mistress is a Shi'ar spy and he is ordered to shoot her. He refuses and kills his commanding officer, and says “This is… unfortunate. Disobeying a direct order is an offense demanding the most severe punishment available. Oh well. Thank God that’s over.” As a ghost he meets his father and destroys his body out of anger because of the high standards that were placed on him. He helped Entropy the offspring of Eternity,to kill their father and destroy the universe, then helped re-create it after Entropy had second thoughts. After the universe was remade everything returned to as it was to before Marv went insane. He is given a second chance and chooses to save the woman before her boyfriend kills her, but then he sees into the far future after she dies and their is a divide among her disciples and a great war begins killing billions. Unable to deal with the weight of his decisions Marv goes insane again.
In order to keep Marv in line Epiphany teaches Rick how to use the Nega-Band connection to cause Marv extreme pain. The drawback to the technique is that the same damage is felt on Ricks end too. Marv and Rick agree to switch places every 24 hours. Bored and insane once again Marv decides to play the role of mad god. On earth a convicted murderer, Coven, is executed but amazingly comes back to life immediately after and he is set free since technically he has served his sentence. He decides that the first thing he is going to do is kill a key witness who testified against him against him in court, Rick Jones. He shoots Rick from afar but when he comes closer to finish him off he finds that Rick has swapped places with Marv. Marv is intrigued by the situation and how the policy of the court system to ignore all evidence that isn't directly presented, he bestows Coven with a fraction of his cosmic power and they set out to find a crime in progress to ajudicate. Flying around New York they find Spider-Man fighting an alien, they use their cosmic power to knock them both unconscious and force them to go to "trial". The smaller alien that Spider-Man was protecting reveals that it was just a weird sexual game between he and the larger alien, an embarrassed Spider-Man agrees to leave but the larger alien threatens Marv and Coven snaps his neck. The smaller alien flees and swears revenge against Captain Marvel.
Back in the Microverse Marv continues playing Judge, Jury, and Executioner when he puts himself in between two lovers in a dispute and after performing a quick marriage and divorce he threatens to kill the man if he doesn't leave the planet but before leaving the man threatens vengeance. Back on earth Rick is attacked by the empowered Coven but he is able to fight him off using a gun he took from the Microverse, Marv takes his powers away in retaliation but Coven is able to overcome Marv and take all of his powers. At that moment on earth and in the Microverse the two aliens who swore vengeance against Marv return to the respective planets with massive fleets backing them up to kill Marv. In the Microverse the aliens found the corpse of Marv and left, on earth the aliens saw Coven who had taken on the appearance of Marv after stealing his powers. Coven threatened the aliens and they attack him, seconds before they fire Marv takes his powers back and Coven is killed. Marv tells Rick that because of his cosmic awareness he had known the outcome to the entire situation and there had never been any danger.
Deeming the Kree, Skrulls, and the Shi'ar a threat to human existence Marv promises to destroy all three species, he is accompanied by Epiphany on his quest. He forces Rick to kill himself for attempting to get in his way but brings him back to life later. The three species decide to annihilate Marv but are convinced by the Eternals to give them a chance to save him from his insanity. Marv and Epiphany travel to Titan and find that everybody is gone, Rick talks to Marv and tells him that Epiphany isn't there and he is just hallucinating.Marv is ambushed by his younger sister Phyla, she has the ability to absorb all forms of energy thrown at her and wants to take the role of Captain Marvel from her brother. Marv is confused because he never had a sister before but he has memories of them growing up together. The rest of the Eternals show up including Marv's thought deceased mother Elysius, she tries explain to him that when he remade reality with Entropy they altered it. Marv rips reality in half on Titan to get rid of his sister and mother but he is also pulled through into the pocket universe where his powers are gone. Elysius explains everything that is happening around him, when Marv remade the universe he brought mulpitple timelines together into one contradicting one. His mother and sister were brought from a reality where Marv had become a great hero and never gone insane, this also explained how all of the events that happened before he remade the universe were still true even though they never technically happened. She also forces Marv to face the fact that he was never insane but had used it as an excuse to escape liability for his actions because he knew he couldn't live up to the expectations placed on him. Marv returns them all to Titan and swears to live up to the name Captain Marvel, Rick tries to congradulate Marv but he seems distracted, because the hallucination of Epiphany is still there telling him that he is insane.
Newly reformed, he sets up shop on Hyperion and now only goes where asked. Due to the entire galaxy fearing him nobody will contact him for help so he decides to help out Rick with his marital problems by secretly broadcasting Rick's song for Marlo from his a private studio to every TV, computer, and radio on earth. Marv also set up a website to download the song from to make Rick money, in less than an hour their are over three million downloads and Rick becomes a millionaire. Marlo hears the song and her already shaky relationship with Moondragon crumbles when she decides to go back to Rick. When Marv tells Rick about the broadcast he is at first furious but quickly forgives him, Marlo then walks through the door and attacks Rick and Phyla. Marv intervenes and she crumbles, Marv uses his cosmic awareness to determine that she is from the future and he uses Titan technology to set out and prevent her fate.
He jumps into the future a few hundred years and finds over ninety percent of earth's population annihilated, the earth was attacked by the Kree, Skrulls, and Shi'ar as soon as earth tried to colonize another planet because they deemed human's too dangerous a species to be allowed to live. Marv meets his immortal but otherwise powerless son Ely and a future version of himself. They are keeping Marlo in a coma in their bunker until they can find a cure for her disease. Marv used the Nega-Bands to fuse his two selves together to combine his limitless power with the incredible knowledge of his future and he kills all the aliens on earth. His future self then tries to annihilate the alien species but Marv takes control and expels him from his body. The people of earth are eternally grateful for his deeds and build a statue in his honor, Marv jumps even further into the future to find the moment when Marlo went insane but instead end up in a strange medieval type earth where Ely is the leader of a ridiculed church dedicated to Captain Marvel. Ely tells him that Marlo was taken from her stasis chamber earlier but Marv sees that he's lying and tries using his cosmic awareness to determine what really happened but Ely reveals that he learned how to turn cosmic powers against their users so Marv switches places with Rick and allows him to interrogate Ely. After a serious beating, Ely fights back by tapping into the power of Rick's Nega-Bands and sending him farther into the future where humans have long since died out and earth is being colonized by aliens. Rick has lost his Nega-Bands and finds that the last record of human existence is a hologram left by Doctor Doom. In this time Ely is with Marlo and they are the last people on earth, Ely is trying to resurrect Magus. Marv resolved to kill his son in his Cipro, thus preventing him from ever growing into the evil, powerful dictator.
After everyone returns to Hyperion Rick and Marlo get back together which allows for Moondragon and Phyla to begin a relationship. Unfortunately the end of their adventures are signaled when Marlo's former employee at Comic Castle, Al, shows up to collect everything. Rick sees everything for what it really is due to his "Comic Awareness"and starts to throw a tantrum. Al is actually Eulogy one of "the seven friendless", a group of cosmic entities that control the universe. Eulogy shows up at the end of all comics to settle all loose ends and collect everything so it can be used again later. He sends Moondragon and Phyla away through a portal before talking to Rick and Marlo. Eulogy undoes the bond between Rick and Marv, takes away Marlo's death wish ability, and tells them what their futures would have been had their adventures gone on. He pulls Marv out of the Microverse and explains to him that the adventures are over. Marv takes some convincing but he agrees to follow Rick and Marlo through the portal after he apologizes to his dad for failing.
Genis later joined the New Thunderbolts, where he was killed by Atlas, healed to a faster and better extent by Baron Zemo with the power of the moonstones, changed his name to "Photon" ( Monica Rambeau changed her name to "Pulsar"), then was killed again to save all of time-and-space.