A timeline of key events in the (updated!) NWABBW universe. This fic cheerfully rejects canon and sets the events of Undertale in 201X, with Chara falling sometime in the past (as opposed to the canon, which places the game at some unknown point in the future, and where Chara is the one who falls in the modern day of 201X). Naturally, I’ve taken 201X to be September 2015, Undertale’s birth year. This timeline will spoil Sans’ backstory for the few people who did not read the original fanfic, but the bulk of those events are ones that you probably anticipated anyway, as they roughly fit within the game’s canon.
There are perhaps some inconsistencies or at least stretches of the imagination here: Justice falling ten years before Frisk may or may not constitute “a long time,” as Toriel says it has been “a human has not fallen down here in a long time” when we first meet her at the start of Undertale. Ten years doesn't seem like it would be so long for a monster as old as Toriel, but we're rolling with it. Technically, we also have no reason to believe the human children fell in the order in which we find their items, but I didn't care enough to play around with that. I guess there's no canon to the order in which the humans fall either way, and it is the order in which they help us defeat Photoshop Flowey, so shrug.
c. 1600 — The war between humans and monsters takes place, and the Barrier is erected, sealing monsterkind underneath Mount Ebott. The former king of monsters is killed in the war, as are his eldest children and immediate heirs. A young Asgore takes the throne as he leads his people toward an uncertain future underground.
c. 1750 — Gaster is appointed Royal Scientist.
October 1919 — On the Surface, Chara is born.
February 1920 — The young prince Asriel is born.
Spring 1929 — Chara falls into the Underground aged nine. They are found by Asriel and go to live with the Dreemurrs. Chara receives coronation a few months later. It is believed they are the Angel from the old prophecy, destined to liberate monsterkind.
Spring 1932 — The Angel Chara takes ill and dies when they are only twelve years old. (The true circumstances behind their death are never discovered by anyone other than Frisk). Asriel absorbs their soul and takes their body to the Surface, but he is attacked by the humans. He staggers home wounded and dies in the throne room, his dust spreading across the garden. In a fit of grief and rage, King Asgore declares war on humanity. Some months later, Queen Toriel disappears into the Ruins but does not seal them off yet.
1940 — The light blue-souled human child falls into the Underground and stays with Toriel for several months. Word of a human in the Underground reaches Asgore. He heads into the Ruins and kills the child. After the death of the Patience child, realizing the lengths to which the King might go to harvest the human souls, Toriel seals the door to the Ruins.
1944 — The orange-souled human child enters the Underground, but only stays with Toriel for a few days before venturing out into the Underground and being killed in Snowdin.
1961 — The dark blue-souled child falls into the Underground. Like the Patience child, the Integrity human stays with Toriel for a few months before heading out into the Underground, and is killed in Waterfall.
1975 — The purple-souled child falls into the Underground. The child is encountered by Doctor W.D. Gaster, who speaks briefly to them. He considers capturing the child to study their soul, but word that a human entered the Underground is already out, so Gaster opts to turn the human in to the Guard, well aware that Asgore would not approve of his conducting experiments on a live human specimen.
1976 — Gaster receives permission from the King to begin studying the souls of the already-deceased humans, to see if he can clone one in order to break the Barrier sooner. He is unsuccessful in this endeavor but begins to toy with the idea of creating some sort of artificial vessel that can break the Barrier prematurely.
1981 — The green-souled child falls into the Underground and stays with Toriel the longest of any of the human children, almost two years.
1983 — After exiting the Ruins, the Kindness human is caught and killed in Hotland, making it further than any of the children who fell down before.
November 1984 — Gaster creates Sans, who is born in November of this year.
March 1992 — Papyrus is born.
September 1992 — The Determination trials begin a couple of months before Sans’ eighth birthday.
1995 — Sans begins to display strange symptoms as a result of the Determination trials. Gaster begins to get new ideas about the possibilities Determination has to offer.
1996 — Gaster isolates a tear in spacetime and begins to study it.
July 1997 — Sans fails to initiate a True Reset and inadvertently causes an explosion of Void energy in the CORE. Gaster and four unfortunate workers who happened to be in the vicinity are erased from existence. Sans takes his brother and flees into an uncertain future.
2000 — The brothers establish themselves in Snowdin.
c. 2004 — The yellow-souled human falls into the Underground and dies in the lower pools of Waterfall.
2006 — Frisk is born on the Surface.
2010 — Alphys builds Mettaton and is appointed Royal Scientist around the same time. A few months later, Sans seeks out the new Royal Scientist’s help in recovering the blueprints to a certain machine.
2012 — Flowey’s Resets begin. Around the same time, the previous Captain of the Royal Guard retires, allowing a twenty-year-old Undyne to take over his position.
2013 — The Amalgamates are created.
September 2015 — The human child Frisk falls into the Underground, and the Barrier is broken.
And it is one year later that our story begins…
