Author note: I do not own any of the intellectual properties related to the Mass Effect series or any other media franchises that are alluded to in this work. This story is a celebration of the imaginative universe belonging to Bioware, that seeks to entertain other fans of the games as well as people who may not be familiar with the games themselves but for whatever reason have taken an interest in the fanfiction. Keep in mind that this fan fic is going to be moderately to highly Alternate Universey, I will ask for the opinions of readers to influence how far I want to go from the established canon, like whether there should be Reapers or not.
Gregorian Calendar date 2147 AD: An exploratory mission on the planet Mars discovers strange material seemingly comprised of atoms that lack protons, thus it is named "Element zero" or "Eezo" in shorthand by members of the scientific community. The discovery is not considered very amazing until its extraordinary properties related to how it releases dark energy when subjected to an electrical current, which physicists hypothesize to have limitless applications. Following this realization, the United Nations Security Council organizes a global effort to send scientific and engineering experts from all across the Earth to Mars for the purpose of tracing Eezo back to it's source and further researching it's applications. The Mars colonies, once simply small sub surface bunker communities, soon find themselves stuffed with people and needing to expand soon.
GCD 2148 AD: The various land surveyors and engineers sent to Mars succeed in finding the source of eezo on Mars, to their shock it is not a naturally formed deposit but rather a leak from an underground alien facility dated to more than 50000 AD. This has deep impacts on the perspective of the entire Human species regarding their place in the universe as it proves that not only has there existed other sentient life in the galaxy, but they might have tampered with our genetics during our transition to a sapient creature. The facility is thoroughly studied, and to the joy of scientists across the planet the computer systems are able to be interacted with in a highly crude, if satisfactory, method. As a result they learn that the aliens were known as "Protheans" and had used Eezo to generate Mass Effect fields that could be used to alter the mass of objects, allowing FTL travel as well as a great many other fantastic feats. Large amounts of refined eezo are found in the facility which the best minds of Homo Sapien Sapiens put to use in developing prototypes for starships and weaponry in case aliens exist that might attack Earth.
GCD 2149: A flotilla of Humanities first eezo powered spacecraft are sent to Pluto to seek out the "mass relay" alluded to in the Prothean Archives. at first arrival the mission seems pointless until they realize that Charon, the moon of the dwarf planet Pluto, is in fact a massive construct enveloped in ice. After freeing the structure from it's millennia long state of orbit around Pluto, a scout ship commanded by Jon Grissom is sent to closely analyze the massive device and learn it's purpose. To the amazement of the flotilla, the ship disappears in a flash of light soon after approaching the Relay, almost sending them into a panic, until Grissom's ship returned a few minutes later with incredible news of being transported 36 light years away in an instant. Immediately the major nations on Earth announce the need for unity in space exploration , eighteen powerful nations signing the Systems Alliance Charter which was given full authority as the sole regulatory agency in charge of defending colonization, exploratory, and scientific expeditions as well as traders.
GCD 2149-2157: The Systems Alliance leads Humanity in a period of rapid expansion utilizing every Mass Relay they discover, establishing more than 80 colonies and discovering many more habitable planets. IT is not only the extrasolar colonies that thrive however, as the resources sent back the the homeworld allow Earth to enter into a golden age of prosperity. On Mars there is also a revolution in society as Mass effect technology allows the creation of surface structures protected from the harsh environment by shielding technology. As Mars was the first place to have the infrastructure to construct and launch eezo powered spacecraft, it also undergoes a transformation from a crowded network of research outposts and vertical farming facilities into an industrial powerhouse. The Martian capacity for constructing spacecraft and the materials required for establishing and developing colonies is second only to Earth and it's lunar factories.
GCD 2157/Galactic Standard Date 700CE: First contact is made with a badly damaged fleet of alien starships arriving in the Shanxi system through the Mass Relay, initially the planetary defense fleet is nervous but after an exchange of standard first contact packages and protocol Communication is made possible when Captain Hannah Shepard agrees to an unusual telepathic ritual with one of the blue aliens. From this the Alliance learns that the aliens are known as Asari, and they are part of a galactic government ruling from an immense space station thousands of light years away, the government is known as the Citadel Council and is mostly influenced by the two founding species; Asari and Salarians. The Asari themselves explain how the Citadel Council's history has been for the most part peaceful until the Citadel year 500 when contact was made with a hostile race of hive minded insect like creatures with space faring capabilities and an insatiable appetite for all other life. What followed was a 300 year long conflict that saw the deaths of tens of billions and the eradication of life on multiple planets, it was only won by the council because the Salarians uplifted a hardy race of militaristic aliens known as Krogan living in the aftermath of a nuclear war on their home planet Tuchanka. The Krogan were not only unique among the Citadel races in that they could confront the Rachni in equal numbers due to their rapid breeding, but also they had an incredibly strong physique capable of withstanding the hostile conditions of Rachni nests on barely hospitable planets. Following their eradication of the Rachni menace, the Krogan were rewarded with a new home planet without the horrible radiation and predators of Tuchanka, their population exploded, requiring more planets every decade to sustain the population and prevent unrest among the warlord leading caste, ambitious leaders could simply establish a new tribe instead of killing the leaders of their own. The council tolerated this for several centuries until eventually the Krogan began staking claim to beautiful garden worlds the Asari or Salarians had plans to annex, resulting in the declaration of war upon the Krogan Clans and the beginning of what had come to be known as the "Krogan Rebellions." The Asari ships that arrived at Shanxi were fleeing from an attack by one of the Krogan clans, and had been sent out to use any means possible to find new species, whether space faring or not, to ally with against the Krogan, as even the combined might of the Council species and associate members was crumbling under the fury of the Krogan hordes. A day after this is communicated to the Systems Alliance Parliament, a fleet of Krogan warships appears in the Shanxi system, eager to crush the remnants of the Asari exploratory fleet. The Alliance used data from the Asari to attempt declaration of neutrality in the conflict, and that the Asari were under their protection until the Parliament decided whether or not to agree to an alliance, The Krogan judged this as being the pathetic cowardice of an Asari like race, fit only to serve the Krogan as slaves. As the Krogan fleet approached with gun ports open, it was clear to the Systems Alliance fleet at Shanxi that neutrality was not going to be accepted.
So that is the first chapter in my first ever fanfiction story, I hope you all have enjoyed, please leave a review about how you it could be improved and feel free to point out any canon flaws i made in this chapter or future installments, though some will be intentional. Next chapter switches from a timeline into an actual third person account of the battle for Shanxi, as ME fans can imagine it will be a lot bloodier with the Krogans instead of Turians. I have begun this as a timeline to get lots of exposition out of the way and also to establish how much of an alternate universe this will be from the start, In any future timelines I will likely switch to another calendar like the Galactic Standard Calendar to make it easier to follow.