Their origin began in the 1970s with a research group under Bella Pagan, a temporal physicist. Their theories on temporal acceleration and parallel evolution were ignored by the scientific community at large, and they eventually turned to the Chilean government for funding. They convinced their providers to lease them the tanker El Conquistador, which was converted into a laboratory for their research. The team dropped off the map after the coup of 1973, which destroyed most records of the transaction (X-Men #191, vol. 2).
The project remained shrouded in mystery until Doctor Casales, a member of the original team, hired the mutants Sabretooth and Pasco to kill his associates. Casales felt remorse over the unethical actions his team had performed, and hoped to erase any evidence of his involvement. After killing Casales, Sabretooth and his associate found the location of the tanker. Unfortunately, they arrived on M-Day. The energies released prematurely alerted the Children, and they came into conflict with the newcomers. Pasco lost his powers and was subsequently killed, while Creed escaped.
The Children became determined to stop Creed before he alerted the entire world to their existence. Five members were sent to kill him: Sangre (the leader of the Children), Serafina, Perro, Fuego and Aguja. In their attempts to capture him, Sangre and Serafina activated a singularity generator that destroyed a small town in Nogales, Mexico. One child survived by Serafina's intervention and was used to convince the media that the X-Men were involved in the destruction. Creed was ambushed by Aguja and Fuego, and was able to escape despite having his healing factor temporarily neutralized. He reached the X-Mansion the same night, seeking asylum.
The members decided to use Northstar and Aurora as tools to kill Sabretooth and the X-Men so they would not have to reveal their presence. They invaded the S.H.I.E.L.D. facility where Northstar and Aurora was being held and slaughtered all of the members. Serafina hacked the interfaces being used to brainwash them, and warped them to the Children's desires. She inserted images of the X-Men into the security footage to cover their tracks, and altered the twins' genetic mutation to enhance their speed and produce an intense explosion of heat when they made physical contact with each other. Northstar and Aurora were set loose against the X-Men, while Serafina and Perro monitored their progress. The surprise attack was nearly successful, as many of the X-Men were seriously injured and Iceman was apparently killed. Cable and Rogue eventually teamed up to stop Northstar, while Aurora was caught off-guard by Mystique and Iceman's reformation. Only after the battle did Cable find out (from Creed) about the Children's mission.
Serafina, seeing their first attempt fail, sent Perro back to the others and infiltrated the mansion with her cloaking abilities. She made her way to Lady Mastermind's hospital bed, and used the latter's abilities to trap Cannonball in a powerful illusion: Sam was married and lived in a idyllic neighborhood. She inserted herself into the illusion as Sam's wife, admittedly because she never knew the pleasures of a sexual relationship. Cannonball eventually became suspicious because of gaps in his "memory" and broke out of the illusion, while Serafina was confronted by Wolverine. She disabled Wolverine's healing factor, making his skeleton poisonous, and defeated Cannonball in short order. She was unable to kill them before being further detected, and retreated back to the Conquistador.
Serafina's failure alerted the X-Men to the Children's involvement. The latter decided that they would have to take drastic steps now their cover was blown. The Conquistador was retrofitted for flight capabilities, and headed for New York to destroy the Xavier Academy. The tanker was detected by the Air Force, but Aguja and Fuego destroyed the jets sent to intercept it. Rogue's X-Men located the ship and attacked them head-on, but were soundly beaten and taken prisoner. Iceman was apparently vaporized by Fuego during the fight.
However, the captured X-Men successfully escaped and fought back. Lady Mastermind projected an illusion that made Aguja look like her, resulting in Fuego killing Aguja by accident. Iceman unexpectedly reformed his body and drained Fuego of all his energy, freezing him solid. Cannonball attempted to appeal to Serafina through the "relationship" they shared in the illusion; after she rejected any notion of having true feelings for him Cannonball grabbed her and drove her into the side of the Conquistador, knocking her out. Mystique shot Sangre with thermite bullets, turning the water in his body into air. Additionally, the X-Men destroyed the Conquistador's weapons. A dying Sangre tried to ram the Conquistador into the school, but was stopped by Cannonball and the ONE Sentinels.
Most of the Children, including Perro, successfully escaped the Conquistador by altering animal carcasses to look like their own bodies. They escaped to Ecuador, settling in an abandoned Sentinel facility once used by Cassandra Nova. They are now led by Cadena, who plans to continue their dreams of universal conquest.
The Children are descended from baseline humanity, but are considered a separate species due to genetic drift. They do not identify themselves with Homo sapiens sapiens (modern humanity), Homo superior superior (a potential subspecies that Vargas claimed to belong to), or Homo sapiens superior (human mutants and changelings). They believe that they are the true inheritors of the Earth. Originally they planned to wait until humanity was wiped out by global catastrophes, but the energies of M-Day prematurely released them. In the past, they planned to wipe out humanity and mutants in order to bring about their destiny; however, since the creation of the Quitado, they no longer see the need to interfere in the affairs of other races (or dimensions), except under certain circumstances. Even though the prominent members have shown no qualms about killing other humans (they apparently view it as exterminating pests), for the most part they do not actively engage in slaughter unless necessary.
Similar to " The World" designed by Weapon Plus, the Conquistador was outfitted to alter time according to the creators' preference. An installed temporal accelerator changed the Conquistador's time in relation with the outside world: over the span of roughly 30-35 years, the Children of the Vault underwent 6000 years of technological and evolutionary advancement. Due to this leap, they have foregone sexual reproduction and produce members asexually. How they raise children is unknown. They utilize a large amount of Spanish in their day-to-day life, to an extent that suggests that they're bilingual, if not dominantly Spanish; their code names are universally Spanish, also.
After their defeat at the hands of the X-men, the remaining Children created the Quitado, a sort of floating city that exists in 'the void between dimensions'. Highly advanced, it faces an energy crisis which could be solved with a mechanism known as Angelfire, a device which utilizes the energy-based powers of 15 individuals to function properly and provide energy with zero waste produced (however, the individuals inside the device would have to remain there forever, somehow never aging but constantly powering the machine). Unfortunately, there only exist 14 candidates that could work as a part of the machine, meaning that it is not a viable alternative as of yet. Currently they utilize an energy source that produces rather dangerous waste, which is ejected from the city via waste interface, ending up in random locations across many dimensions (due to the inter-dimensional nature of the city), one of which is stated to have been Mumbai, which suffered severe storms and caused large numbers of people to become ill. It is unknown if waste is still ending up in Mumbai.
The typical clothing worn by the Children of the Vault is unknown; most of the members currently seen appear to wear some sort of uniform, or 'superhero costume', that is unique to them alone. However, with introduction of the Quitado, at least two individuals have been seen wearing what is not likely to be considered a super-hero costume; Luz, who sports an outfit that would be impractical and hindersome in battle, and Corregidora, who was seen in what could be the uniform of a guard.
Currently they have roughly 3000 members (X-Men #193).
The Children do not appear to have inherent powers due to their changed biology, unlike mutants. Their technological advancement allows them to manufacture suits that replicate a variety of superhuman power-sets. Their suits are powered by an internal battery, and lose those powers when the battery runs out.
Sangre, the original leader of the children, had aquakinetic abilities. He was able to produce bubbles from his "skin" capable of suffocating individuals. His aquatic body was also very resistant to harm and could absorb bullets effortlessly. He was killed by Mystique when she shot him with thermite bullets.
Fuego was a pyrokinetic who drew heat from the environment to maintain a fiery form similar to Ghost Rider. He could feed upon the flames of Rogue, who possessed Sunfire's power template at the time, and was able to vaporize Iceman's body through a positive feedback loop. Iceman reformed and essentially froze him to death.
Aguja had various energy-based powers. She could create forcefields and energy blasts strong enough to decimate fighter jets. She also seemed to possess the ability to slow down Sabertooth's healing factor with such blasts. Under Lady Mastermind's illusion, Fuego was tricked into incinerating her.
Cadena, the current leader, has a globe of electricity around her head that she can manipulate into electrical chains. She is alive and now the leader of the Children. Cadena in Spanish is the Chain.
Perro possessed great superhuman strength, durability, and gravity manipulation. Sabertooth described his punch as the hardest he has ever felt. He was able to completely stop Cannonball's momentum with his power. Currently he is still alive. In Spanish, Perro is the Dog.
Serafina has a instinctual understanding and control of systems, both technological and biological. She can interface with computer systems and machinery, process and delete information at will, hack into transmission feeds from a distance, selectively block out electromagnetic transmissions, and connect with individuals who are hooked up with technology. She is capable of detecting genetic and bio-chemical data at the sub-atomic level, granting her a measure of psychometry. She is also capable of mind-control and altering the biology of targets, even controlling and enhancing mutant abilities beyond their original parameters. She was rammed into the Conquistador's hull by Cannonball, and was thought dead. However, she later re-appears as part of a team assembled to retrieve Luz, a young runaway member.
Luz is a strong-willed, free-spirited young citizen of the Quitado, the new home of the Children of the Vault. She wields light-based abilities, and is described as being phenomenally powerful, having displayed the potential to create solid light constructs (that last for an indefinate period of time), move at the speed of light, render light-based weaponry or armor useless, and 'sculpt light waves into finite, coherent patterns'. Magneto is quoted as saying she possesses the type of power usually found in supernovas. Luz in Spanish is light.
Rana possesses the ability to physically enter and manipulate other characters either to attack them from the inside or possess them. Rana in Spanish is the Frog.
Corregidora is possibly the head of security in the Quitado. She was seen attempting to prevent the escape of Luz. Corregidora is Spanish for magistrate.
Martillo is one of the larger more physically imposing of the Children of the Vault. He carries a large magnetic teleporting hammer and he also possesses the super strength required to wield it. Martillo is spanish for hammer
Olvido is an aqua haired member covered in white bandage like cloth. He is connected with the Antimatter Universe (probably referring to the Negative Zone) and can use that connection to absorb and redirect energy. He has shown the ability to neutralize powerful energy users like Magneto. Olvido in Spanish is the void.