Board Thread:General Discussion/@comment-32182236-20181101220519/@comment-31536324-20181107002245

Then again though, in Undertale, the FILE was transferred from one entity to another; a completely new FILE would have to be made for the new user. There is our FILE and the Flowey's World FILE after he takes the power to SAVE back after all.

In Deltarune, it's the FILE of the person who currently has being overwritten while they're possessed.