An argument I’d like to work through at some point, when I can think how best to present it:

All three routes are the result of three entities working in concert: Frisk, Chara, and the Player. No route is possible without all three contributing in some way. However, the Pacifist Route “belongs” to Frisk, the No Mercy Route “belongs” to the Player, and the Neutral routes “belong” to Chara, based on who is acknowledged to be present and how.