Board Thread:General Discussion/@comment-27984457-20160922193051/@comment-27701762-20160923204628

Alkhor-dm wrote: Ty.

Another question: who set, than 1 human soul not enougth, to go thrue barrier? (why Alfis tells it to Frisk?) and how then Frisk leaving in teutral rout, with 1 human soul only? The information that it requires a human and a monster soul is only introduced from Alphys, through can be read back into the phrase "powerful soul" from the quote I posted above. The information is confirmed, though, by the fact that A) Chara does not leave of their own accord at any point in time, and B) the only other being that we know has left the Barrier is Asriel, once he absorbed Chara's soul.

As for the Neutral Route, there is no confirmation that Frisk actually gets through the Barrier. While it is one possible explanation, there have been plenty of other explanations put forth, such as that they are trapped in a pocket dimension created by Photoshop Flowey, that they are still trapped somewhere in the Underground, that they are trapped within the Barrier itself, or that they are actually dead.