Chara's not evil. Chara's an abused child who hated Humanity but loved the Monster people that showed them so much love and kindness. After accidentally poisoning Asgore by mixing up Cups of Butter with Buttercups (Something any child under the age of 10 would do) they decide to free their family and friends by dying by buttercups (While also punishing themselves with what they felt they deserved for their mistake) and breaking the barrier with 7 human souls. They also wanted to see the flowers from their village one more time showing their love for flowers and the only Happy memories they have of the surface. After they carried their body to the flowerbed the humans assumed Asriel had murdered them which incited their rage as they didn't even give him a chance to explain himself. Because of this they wanted to use their full power on the humans to protect their brother, but Asriel wouldn't let them go through with it and carried their body back to the Underground after suffering mortal damage.







When Asriel's soul shatters Chara's soul shatters as well due to being combined with his. When Frisk falls underground they land on top of Chara's dead body and their DETERMINATION from their SOUL awakens Chara's Spirit from inside their body (Which was trapped there like Asriel's Spirit was trapped inside of the flower he fell on top of).





If the Player doesn't interfere Frisk's mission to save everyone and return to the surface then Frisk is able to show Chara that there are good humans out there and that they can rest in peace with the knowledge that everyone they love has been saved and is happy now (The game implies Frisk will SAVE Asriel as well by finding a way to recreate his soul with several dialogue boxes as well as the theme of the game and the "Will to change fate and defy history" being what the human soul is all about (And Toriel saying that whenever the past humans fell down she got the feeling she already knew them, like she was meeting an old friend for the first time (Resetting after Frisk tells her their preferred pie topping causes this) proving that the previous humans had the power of "RESET, SAVE, And LOAD" as well proving that those powers come not from the Player (Who is a non entity in the True Pacifist Route which is the "actual" route), But they lacked the "DETERMINATION" that Frisk has to never give up (And Asriel stating that he's observed that Frisk will do it during his final battle because they "Never give up" "Because they want a Happy Ending" "Because they love their friends".





It's only by the Player forcing Frisk to kill in the Genocide (Which is a what if route rather than an actually possible route) that Chara becomes corrupted and turns into what you see at the end of that route.

