Following the death of Chara, Asriel brings them to the village where they lived once so they can see the flowers in the centre. The humans attacked Asriel but before he could sustain lethal injuries which lead to his death in the original Undertale, he lashes out in grief and attacks a few of the humans, leading the rest to fall back and let him return to the Underground in without further intervention. Upon his return to the underground, the King (Asgore) and Queen (Toriel) are incredibly disapproving of his actions. However, Asgore still declares war on humanity due to his opinion on their attitude to his son. Toriel split’s up with Asgore and goes into exile in the Ruins. A few of the humans fall with Asriel growing older together with his father, however the royal scientist’s experiments on the soul which had been going on over the time in which the humans fell led Asriel to believe that with the power of the human souls he could resurrect Chara and if not, avenge their death upon humanity. He soon realised that his goal would not be achieved with his current status and his status by the time the final human fell (Asgore would still be alive and king by the time the final human’s soul was in his hands). He used the power of a reset from Chara’s soul which was bonded to his to return to the moment where he brought Chara’s body to the human village. In this reset, instead of letting his parents live, he intended to kill them. He was powerful with the power of the human soul, but not enough to kill his parents. He took many resets to finally kill them, but in the final reset. Asgore had caught on to what he was doing and faked his own death, Toriel believed this but also faked her own death. The two believed each other were dead but both survived. Toriel went into exile in the Ruins and Asgore in exile in a secret tunnel system under New Home which Asriel was never aware of.

During his reign, Asriel became a dictator and indoctrinated most citizens into believing he was supreme and a hero to the monsters, he gave himself the moniker “King Dreemurr”

Sometime between when the human possessing the yellow soul and Frisk fell, the royal scientist conducted experiments with the 6 souls to resurrect Chara. However, the 6 humans were instead brought back to life, but as undead spirits instead of real humans. The royal scientist was aware but never told anyone, not even the King was told. The spirits tormented the King through dreams, hallucinations and other psychological tormenting methods due to their inability to interfere physically with most people.