Hey guys I's not new here but this is the first time I've published anything other than super short crap. All reviews will help and I will try to reply. Bring on the flames because i'm ready to make s'mores.

It's just a timeline but you could skip it if you want. This has some big AU stuff in the very beginnings and there is some pretty important explanations and info here so you might want to check it out. I'm going to reference mostly Halo times, because I don't know as much about Mass Effect history

Sorry again, I posted an unfinished version of the first chapter. It is now fully complete.

- Out of the darkness - ? BCE - Milky Way and Andromeda galaxy

Precursors and Leviathans evolved at relatively the same time and advanced at a similar pace. Precursors in the Milky Way and the Leviathans in the Andromeda galaxy.

- Reign of Precursors and Leviathans - 1,000,000,000 BCE - Milky Way and Andromeda galaxy

Precursors and Leviathans both achieved technological tier 0 in the Forerunner Technological Achievement scale and dominated everything in their respective galaxies with no species strong enough to challenge.

- First contact gone wrong - 500,000,000 BCE - Large Magellanic Cloud

First contact goes uneventful as both civilizations have theorized that advanced life existed in other galaxies. First contact info was made known to everyone in the two galaxies. However, the beginnings of a great conflict were ignited when the two opposing cultures learn more about each other. The Leviathans believe they are and always will be the apex species with total control being the best way for peace, while the precursors think that legacy races such as the forerunner and humans are a better way of having peace. This causes the Precursors to take offense because of the insult of this idea to the Mantel while the Leviathans find it intolerable that a species would challenge their dominance A cold war erupts.

- Apex of the cold war - 400,000,000 BCE - Milky Way and Andromeda galaxy

After a massive military buildup of millions of years in length, a war is right on the horizon, and most people believe that it is inevitable. During this time, the Precursors researched a super-virus capable of assimilating all known life and began to weaponize it against the Leviathans. The Flood was born. The Leviathans create both a solution to the AI problem in their own galaxy, as well as to be a technological terror weapon to be used against the Precursors. The Reapers were created.

- Shot heard 'round the local galaxy cluster - 300,000,000 BCE - Large Magellanic Cloud

The firsts shot were fired in anger between the Precursors and the Leviathans. A war on a scale never before seen erupts. The area in and around the Large Magellanic Cloud become filled with debris. Over 40% of the Large Magellanic Cloud was reduced to sub atomic particles in the first few hundred years of the conflict.

- The waring years - 250,000,000 BCE - The local galaxy cluster

Super-large portions of all galaxies in the area were destroyed. Around two thirds of both races was annihilated. Both Precursors and Leviathans underestimated their opponents. Now active deployment of both the Flood and the Reapers begin. A climax was reached. The Leviathans steal genetic codes of humans from the Precursors.

- In the place of gods come demons - 150,000,000 BCE - The Milky Way and Andromeda galaxies, as well as the Large Magellanic Cloud

During the years when the Flood and the Reapers fight each other in a stalemate in the void between galaxies, both races begin to replace lost planets, stars, and solar systems. When the Flood and the Reapers turn on their own makers, the reparation is 95% complete, but leaves both race exhausted when they get betrayed.

- The end of time - 100,000,000 BCE - The Milky Way and Andromeda galaxy

The Precursors are completely assimilated by the flood, although their genetic records and species preserved by their AI's. The reapers defeat the Leviathans leaving only several in hiding and begin the Cycle. The Reapers then leave to outside the Andromeda galaxy to wait and the Flood leave to go to the Large Magellanic Cloud.

- New beginnings - 100,000,000 to 1,000,000 BCE - Milky Way and Andromeda galaxy

The Flood in their Precursor capsule ships return to a powdery white molecular state after millions of years of starvation. Meanwhile, the Cycle has been going along for a tremendously long time without trouble for the Reapers. The Precursor AI's reseeded the Milky Way galaxy of life in a way similar to what the Forerunners.

- Between the times - 1,000,000 BCE to 2557 AD - Milky Way and Andromeda galaxy

Events of books, cannon, and games starting from the beginning of the Forerunners up until the end of Halo 4. Events of books, cannon, and games starting from the Protheans up until Mass Effect 3. Shepard manages to destroy the Reapers for good, without destroying the Mass Relays.

- Second contact - 2560/2190 - Large Magellanic Cloud, Milky Way, and Andromeda galaxy

After discovering Requiem in 2557, the UNSC wages war on the newly freed forces of the Didact. Also, the Storm Covenant shows up in force along with an opposing Covenant Loyalist fleet. Inside the UNSC, Outer colonies, thought to be lost, again begin to rebel with help from a united armed forces of leftover Frieden and Koslovic hardliners now allied for a common goal. To separate from the UNSC. This proves to be a challenge for the UNSC even with the Covenant Separatist as allies. Even more alarmingly, new research by top UNSC scientists on Precursor tech from both Requiem and Onyx reveals shocking evidence of a whole new galaxy brimming with life, and slipspace gates leading right to them. After the defeat of the Reapers, the Mass Effect galaxy is in a state of prosperity and peace, but with new research with Reaper technology, and Leviathan ruins, scientists discover a mysterious "11th dimension" of space, as well as evidence of life in another galaxy. The most shocking discovery, however, is an ancient Mass Relay, hidden for millions of years and has coordinates that lead to another galaxy.

NOTE: A combination of Mass Effect and Halo tech was used by the Precursors and Leviathans for maximum efficiency. However, the Precursors preferred Halo tech while the Leviathans used Mass Effect tech more . When both species disappeared from their respective galaxies, the technology that they left behind was the tech from their strong side.

Thanks for reading. I will try to update once every week. Please give me some criticism about whats going on but give some flames I could use. Again sorry, I posted an unfinished version of this chapter, but I fixed it.