Something I have yet to get a grip on: At the end of Pacifist run Asriel breaks the barrier and then returns to a flower. This doesn’t make sense. Where did the human souls go, and wouldn’t he still have them? Couldn’t he return to being asriel with just one soul? This has been keeping me up at night for far too long now. Heck, I’m typing this right now at 11:30 pm!
(undertale spoilers)
Asriel would not have the souls because he returned them.
The human souls, however, did not return to the coffins. These are empty at the end of the pacifist route. More than likely, the souls have moved on. This may conflict with the idea that human souls persist after death. However, it wouldn’t make sense for human souls to persist on earth forever. The monsters could easily acquire human souls on the surface if this was the case.
» read more: why are the coffins open?
Flowey cannot return to being Asriel with just one soul – he needs both the human and monster souls he absorbed. While the human souls may give him the power to change forms, the monster souls are what allows him to feel compassion. More importantly, Asriel would not choose to stay as himself at the expense of another soul.
» read more: how to bring asriel back
