Hope is the first mutant to be born after the Decimation, an event in which the Scarlet Witch uses her reality-altering superpower to turn all but 198 of the world's mutants into regular, depowered humans. The moment Hope is born, the mutant-locating computer Cerebro explodes, and soon afterwards the hunt for her begins.
Hope's town is attacked by the Purifiers, who use information given to them by the time-traveling Nimrod who warns them of her arrival. Although all the children in town are murdered by the Purifiers, the X-Man Cable manages to save Hope. According to Cable, the baby is a Messianic figure destined to save both mutant and humankind. The Purifiers and Bishop, however, recall a timeline in which Hope will become the mutant equivalent of the Antichrist, and kill a million humans in an instant. This event, known as the "Six Second War", will turn humanity against mutants once again and lead into a new era of mutant persecution, creating a similar dark timeline into which Bishop is born.
Later, the baby is kidnapped by the Marauders and delivered to the mutant Mystique who is disguised as Mister Sinister. Mystique takes the baby and makes her touch the comatose Rogue with the intention of waking her from her coma. The mutant Gambit intervenes and takes Hope from Mystique. Believing the baby has died during her rescue, Gambit is amazed to find not only is the baby unharmed, but also Rogue has been awakened from her coma. After an intense battle between the Marauders, the X-Men and Predator X, X-Men leader Cyclops decides the baby would be better off with his son Cable, and allows him to take her to the future. However, an adamant Bishop decides to track Cable and the baby through time in order to kill her and prevent the bleak future of his own timeline from happening.
During one of the first battles with Bishop, Cable's time traveling device is damaged, so he can only jump into the future, instead of the past, when he needs to escape Bishop each time he finds them. After several jumps into the future, it is revealed that Cable has taken her to the secluded safe haven of New Liberty in the future, where Cable marries a woman named Hope, who is like a mother to the mutant baby. Finding relative peace there, he raises her with Hope until she is seven years old. But then New Liberty is invaded by humanoid insects who called themselves the United States Army, later calling themselves humanoid Blattarians. Cable fights them and leaves New Liberty with his wife and her in order to make sure New Liberty does not fall. After spending months in the wasteland, the family is attacked by the president of the insects, whom Hope manages to save her family from by stabbing the insect in his weak spot, since she has been watching Cable fight. Cable questions the president where he finds out that Bishop, in order to find Hope in the future, has destroyed all the continents in the world and left them uninhabitable, except North America, in order to box them in, find her and kill her. Cable kills the president, and the family moves on. The family encounters a settlement, but are met with resistance. Cable takes care of them easily, but not fast enough, as Hope is shot and dies in Cable's arms while the girl watches. The girl sees Cable bury the closest thing she ever had to a mother and departs with him. After arriving at a church, the pastor asks the name of the child. In that moment, Cable decides to name her Hope Summers, in honor of her adoptive mother.
In the Messiah War storyline, which ran through Cable and X-Force, Hope Summers was the center of conflict between the forces of Stryfe, Cable, and X-Force. The Messiah War was part of a three-part story that began with X-Men: Messiah Complex. During the Messiah War, Hope was kidnapped by Cable's clone Stryfe, in league with Bishop. Hope watched as Stryfe tortured Warpath until Cable, Wolverine and Elixir came to their rescue. In the following fight, Hope survived along with the rest of X-Force and Cable, though Bishop lost an eye to Wolverine and had his time travel device damaged. When Cable and Hope were forced to time travel again, Hope resisted because she wanted to stay with X-23 and Elixir, with whom she had bonded during the events of Messiah War.
She kicked Cable in mid-jump, stranding herself and Cable two years apart. They eventually reunited, with Hope now 11 years old instead of nine.
In the four part series A Girl Called Hope, Hope watches over Cable as he sleeps, and she says "I would come back from the dead to kill them," referring to anyone who would harm Cable, with the Phoenix emblem reflecting in Hope's eyes again as she looks in the fire. As the short series closes, it is revealed that Hope slaughtered many of the evolved wolves in order to keep Cable safe. A promotional image for the event was released depicting two versions of Hope: one angelic, emphasizing her role as a savior; the other as evil and surrounded by the Phoenix Force, depicting her as a destroyer.
During the "X-Men: Second Coming" story arc Hope manifests various X-Men powers such as Armor's psionic armor and Colossus's organic steel and kills Lang and Creed. Nightcrawler saves her from Bastion, dying in the process. With the assistance of the X-Men, she eradicates Bastion and shatters the dome surrounding the city. At a celebratory bonfire, Emma Frost notices the flames around Hope take the shape of the Phoenix, and triggers a flashback to the Sisterhood storyline where Jean freed her from Lady Mastermind's illusion after giving her the warning to prepare. Seized with terror, Emma runs to Cyclops to warn him but before she can, Cyclops tells her that Cerebro has found five new mutants that have appeared around the globe.
After the events of Second Coming, five new mutants are detected by Cerebro, Hope is then tasked with the mission to find and help these "Five Lights". Hope finds the first of the Five Lights in Canada attempting to kill herself by jumping off a building. Hope touches the girl, Laurie Tromette, whose mutation is jump started (a power display similar to Sage's) and she develops an ability to fly. Introducing herself, she also agrees to follow Hope.
Later she is called to Mexico by Cecilia Reyes and Psylocke where the second of the Five Lights lives. This new mutant, a boy called Gabriel Cohuelo, whose speed powers caused him to move so fast he had become invisible to the naked eye. Psylocke taps into Cecilia's powers to create a force field around his room so they would not lose him before Hope Summers could arrive to help. Hope manages to help him gather control of his abilities however it is also revealed that his powers made him age slightly.
Accompanied by Storm, Hope finds the third of the Five Lights praying in a small church in Nigeria, surrounded by armed men who wish to kill her as they believe she is a "witch child", due to her power over fire and ice manifesting. Hope manages to help this new mutant, a girl named Idie Okonkwo calm herself and gather control of her abilities. As Storm and Hope proceed to leave with Idie the men attack, but Idie protects them from harm using her ability over fire and destroys the men's vehicles. She then opens her eyes to reveal her right pupil is blue (ice) and her left pupil is orange (fire).
Later Rogue, Hope, and the Lights arrive in Miami Beach to search for the fourth Light, a boy named Teon, in the hope of having him join the X-Men. Their first interaction with Teon results in the feral boy's attempt at "mating" with Hope. A battle ensues and is promptly finished by Hope who uses her power to tame Teon. From this point, Teon views her as his Master.
In the series Generation Hope, Hope and the four "Lights" along with Rogue, Cyclops and Wolverine travel to Tokyo to find and help the fifth so-called "Light," a mutant boy called Kenji Uedo. Like the four new mutants to emerge since M-Day, Kenji's mutant powers manifested and caused some horrible side effects. He impales his agent with a tendril when the agent pressured him about his contribution for the "Future is a Four-Letter Word" event. He burst through the apartment building and onto the street where Cyclops and Wolverine are investigating. Kenji pulls down the Blackbird carrying Rogue, Hope and the rest of the Lights. Teon takes off after one of Kenji's tendrils and tears it apart. He releases a girl trapped inside but is utterly ineffective against him.
Hope attempts to make contact with Kenji in order to complete his transformation but he seemingly avoids her touch. She presses on after him and encounters him within his apartment. She tells him she's there to help and he explains how his "throat slid out of his neck and danced like an eel when this began" and NOW she's here to help. He turns around and grabs Hope and a large explosion follows. It turns out to be telepathic message. Then she falls from the sky and Gabriel saves her although she's unconscious. Kenji is blasted away by Idie and Cyclops and Wolverine try to kill him but Hope awakes and with the Lights tries to make contact with Kenji and she is successful. She passes out from strain.
Later, she and the five Lights travel to Utopia, where they all decide to stay to hone their powers. After Doctor Nemesis examines Hope and four of the Lights and determines the specifications of each of their powers, Hope and Gabriel share a kiss during a moment of privacy. Soon afterwards, after training the Lights to use guns, Magneto introduces Hope to his "old and dear friend," Charles Xavier. Hope takes issue with Charles calling his school a "School for Gifted Youngsters," thinking that it just increases the line between human and mutant. Instead, she suggests that a better future would dissolve the "us and them" mentality all together.
While in one of Emma Frost's classes, Hope decides that what she is learning isn't useful to her, and she leads the Lights out of the classroom. Frost tries to stop them, but Hope just tells her to stay out of her mind and out of her way. Back at her quarters, Hope gets a letter from Hank McCoy, telling her that while most of the people on Utopia are good, they will still try and craft her in their image, and that her best course of action would be to leave. Spurred on by the letter, Hope goes and talks to Wolverine, but Logan simply tells her that she's not a fool, and he wants to keep Hope at arm's length for her safety. Hope then goes to see Cyclops, whom she tells that she will welcome his support, but he should stay out of her way; if any of that changes, Hope and the Lights leave Utopia. Cyclops accepts this agreement, telling Hope that he isn't a jailor and that she and the Lights are welcome to come and go however they like.
In AvX, Hope is targeted by the Phoenix Force. The Avengers want to take her into custody to protect her from the Phoenix Force, but the X-Men want her to be able to accept the Phoenix Force as it could help revive the dwindling mutant "race". As the two teams start fighting over this, Cyclops orders Emma to take Hope away so she could be safe. As the fight continues Wolverine and Spider-Man sneak into the building only to be confronted by a fiery Hope Summers, around her were the unconscious teammates from Generation Hope. As Wolverine moved to apparently kill Hope, he's overwhelmed by Hope who uses the power of Phoenix on him and escape the compound. While on the run, Hope creates a device that camouflages her power signature and makes her untraceable. After stealing a ship, she strikes a deal with Wolverine. Essentially, she wants the opportunity to contain the Phoenix Force, but if she is unable to do so then she will allow Wolverine to kill her. However, Hope is betrayed when Wolverine alerts the Avengers to her scheme. The team meets Hope and Wolverine on the Blue Area of the Moon. Before they can contain Hope, the X-Men also arrive. The Phoenix force arrives and, instead of possessing Hope, possess each of the five X-Men present. They take her now comatose body back to Earth and, as one, declare plans to heal her. However, she is subsequently rescued by the Avengers and the Scarlet Witch, who take her away to safety, with Iron Fist suggesting that she hide in the city of K'unn-Lunn.
Having learned about a previous Phoenix host who was also trained to become the Iron Fist of her era, Hope visits Yu-Ti, but Yu-Ti is unable to help her directly, instead instructing her to learn from Spider-Man based on a vision he had. Although uncertain what he can teach her, Spider-Man proceeds to tell Hope about his mantra of great power requiring great responsibility, giving her more to think about in her role as the host for the Phoenix. Spider-Man later teaches her about patience, and waiting for one's moment when it comes, and to step up to the challenge. Guided by these lessons, Hope fights alongside the Scarlet Witch against Cyclops when he takes on the full power of the Phoenix Force and ascends to Dark Phoenix as he kills Professor X, allowing her to not only take on the power of the Phoenix and restore the mutant race, but also have the power to give up that power afterwards. With her destiny fulfilled, she is shown departing Utopia to find a new place for herself.