Board Thread:General Discussion/@comment-27907368-20160323193924/@comment-5460233-20160610110306

GetYourFix wrote:

4. Sans and Papyrus know a lot more than the other characters - Sans chooses to become a lazybones, Papyrus a crazybones.

5. Papyrus is actually a kid.

7. The red SOUL does not represent Determination but actually represents "Fate."

The Red soul thing makes great sense since Chara and Frisk (possibly inderectly) decided the fate of the underground.