Board Thread:General Discussion/@comment-27907368-20160323193924/@comment-26887879-20160424113214

Frisk is Chara's reincarnation. As soon as they fall, their determination partally awokens memories of their previous life, that's why Frisk has some of Chara's flashbacks (like a scene where they hear Asriel's voice after Undyne throws them in the garbage dump). Like with Frisk, Chara's personallity is influenced buy the player's actions. The more you kill, the stronger Chara's presence is, and during genocide route, they are able to fully replace Frisk and even take control from the Player. However, Frisk's soul isn't part of them anymore and much like Flowey they can't have feelings anymore, that's why they turn into a "demon" after the Genocide route.

If player chooses not to kill, they can't gain any power/control, but they can narrate to their previous life and the player...