Board Thread:General Discussion/@comment-35951900-20181123220830/@comment-32182236-20181204140458

We don't really know. Kindness might have been looking to befriend the monsters, and perhaps end everyone's suffering, Perserverance might have wanted to study the nature of the mountain, taking notes in their notebook..

As for Frisk, that's up for player interpretation, seeing as the player is Frisk. However, someone managed to make a very compelling reason for Frisk to do what they did (At least in the Pacifist Route):https://m.youtube.com/watch?v=0mqY5lrd0uw

In Genocide, their reason is pretty simple:Exterminate the monster population..