The following story is bases on the following changes to the Fallout time line and events that occurred in Fallout New Vegas based on my interpretation of the NCR and their role in said events and how they end up effecting the events of Fallout 4. As a warning this story is going to paint both the NCR and Brotherhood of Steel as villains and overall bad people so don't read this just to complain about my fictional preferences. Also if you want to jump right to the story go on to chapter 2. Disclaimer: I own no elements of the Fallout series they belong to Bethesda(Fallout 4) and Obsidian(Fallout New Vegas). Also event of Fallout 4 are based on a quick play through I did so things might be missing like companions and side quest. Also the sole survivor's last name will be Carter. Slanted text is flashbacks and dreams.
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The Time line
2077: The Carter family enter Vault 111 as nuclear fire engulfs the world.
Shortly after the vault begins its experiment with cryostasis.
Time Skip
2250:Ulysses meets the courier(Kira) and defects from the Legion.
2251:Kira brings Ulysses to her home in the Divide where they work to build a community.
2252:Kira and Ulysses are married.
The Divide begins to thrive.
2255:Bishop is born in the Divide with weak health.
2258:Kira seeks out Vaults in the Mojave for ways to improve Bishop's health.
Ulysses and Bishop remain in the Divide.
2260:Ulysses and Bishop join Kira in the Divide.
Homestead established at Wolfhorn Ranch.
2261:Ulysses helps reestablish the Arizona Rangers(a Vegas militia).
The NCR detonate the Divide via prewar tech. None survive.
2263:The events of Fallout New Vegas occur.
Kira doesn't lose her memories.
Results in independent Vegas with benevolently ruling.
The NCR and the Legion begin to fall apart.
Remnants of the Legion investigate rumors of Ulysses involvement.
Kira pacifies the Think Tank, who become allies.
Think Tank begin investigating ways to improve Bishop's health.
2263:Kira, Ulysses and Bishop move to Big Mountain.
NCR quickly reorganize and begin encroaching on Vegas borders.
2264:The Legion unites under a new Ceaser and begin terrorizing the NCR on the borders and Vegas itself.
The Legion confirm Ulysses' role in their downfall and begin to hunt him.
NCR create alliance with the Brotherhood of Steel(BoS) and establish main base at Hidden Valley.
The NCR identify Kira as a person of interest due to her access to the Lucky 38 and begin to hunt her.
Kira and Ulysses return to the Mojave to investigate the NCR and the Legion threat to the Mojave.
Think Tank begin to develop a serum and treatment to improve Bishop's health.
2266:After careful observation of the NCR and Legion Ulysses and Kira begin planning counter measure against both forces.
The Think Tank complete the serum and develop a method of treatment.
Bishop's treatments commence.
Joshua Graham eliminate the white legs and rebuilds New Canaan.
2267:Chemical treatment succeeds, Bishop's health greatly improves as well as positive side effects.
Effects include: Reinforced bones
Enhanced muscle mass
Enhanced Perception and Agility
Greatly improved disease and poison resistance
Bishop begins to study medical applications and methods
Ulysses and Kira uncover that the NCR was responsible for the destruction of the Divide.
2268:Kira and Ulysses receive news of Bishop's improved condition.
Ulysses sets out to bring his son home.
Kira works to gain allies, the following are recruited:
The Great Khans
The Boomers
The Strip(Lead by )
Jacobs Town
The Arizona Rangers
New Canaan(Lead by Joshua Graham)
2268:Kira, Ulysses and Bishop are happily reunited.
The family set up main operations in Camp Mccarren.
Kira temporarily becomes leader of New Vegas forces.
Kira and Ulysses begin Bishop's combat training.
NCR and Legion activity elevate.
2271:Bishop becomes ideal soldier.
Bishop prevents the NCR-BoS alliance from occupying and attaining a foothold at Helios One.
Bishop eliminates the Legion forces at Nelson and dismantles the Legion slave trade in Vegas.
Vegas forces discover main base of Legion operations in Bunker Hill.
NCR scientist Vivian discovers unknown chemical compound in Bishop's blood that becomes and becomes a high priority of acquisition to the NCR.
2272:New Vegas allies launch campaign to defend Vegas and destroy their enemies.
NCR-BoS alliance take Nipton and begin preparations for operation Steel Soldier.
Kira, Ulysses, Bishop and the Great Khans battle and defeat the Legion at Bunker Hill.
2273:NCR-BoS alliance launch operation Steel Soldier and successfully capture Bishop.
NCR covertly transport Bishop to Hidden Valley.
Doctor Vivian conducts progressively cruel experiments to reproduce the serum in Bishop's blood.
Ulysses and Kira become enraged as they searched for their missing son.
2274:Kira and Ulysses find the NCR-BoS base at Hidden Valley.
A plan of attack is quickly organized.
The forces of Jacobs Town and the Arizona Rangers join Ulysses and Kira in their attack.
The battle is won and Bishop is successfully recovered.
The NCR fails to recreate the serum.
The NCR-BoS alliance begins to suffer due to infighting.
2276:The New Vegas forces wipe out the remaining NCR-BoS forces.
Allies disband but remain vigilant against threats to their home.
Kira returns leadership of Vegas back over to Mr. House.
Bishop successfully recovers from NCR experimentation.
NCR-BoS alliance collapses due to increasing distrust and infighting.
NCR continues to hunt Bishop with increasing desperation.
Ulysses, Kira and Bishop leave the Mojave being pursued by the remaining NCR forces.
They flee to the Common Wealth in search of safety.
2277:The family reaches Sanctuary Hills as NCR forces continue to their pursuit.
Bishop is caught in mortar fire from a Fatman wielding NCR soldier.
NCR set up base in Concord.
The family takes cover in Vault 111.
Badly injured a desperate decision is made.
Bishop is placed in a cryo pod as his parents deal with the NCR.
2287:Fallout 4 begins