Canon Chara

After falling underground, Chara was welcomed in by Toriel and Asgore as a second son and was treated with equal respect to his biological son, Asriel. Chara and Asriel became best friends. In New Home, on a Pacifist or Neutral-Pacifist route, some monsters appear and tell the protagonist how Chara filled the underground with hope. One day, after suffering a terminal illness from consuming golden flower petals, Chara expressed a desire to see the golden flowers found in they home village. On a tape found in the True Lab, it is revealed that Chara actually committed suicide by eating several golden flowers. Upon his death, Chara's soul was absorbed by Asriel, and they shared control over one body. Asriel carried Chara's body to the other side of the barrier. Asriel placed Chara on a bed of golden flowers, the humans saw Asriel that way, and thought he had killed them, so they killed him. Chara's motives in this situation are uncertain. However, on the Genocide Route, Flowey tells Chara that they must finish what they started. Flowey also adds: "Despite everything... In this world it's still kill or be killed!". Asriel tells Frisk that he came up with this philosophy because their resistance to Chara led to both of them being killed. At the end of the Genocide Route, Chara says little about Asriel's "betrayal": "At first, I was so confused. Our plan had failed, hadn't it?"

Though initially cast in a sympathetic light, Asriel admits at the end of the True Pacifist Route that Chara "wasn't really the best person." Asriel says that Chara climbed Mount Ebott for an unfortunate reason, and adds that they hated humanity. Chara never told Asriel why they had so much hatred. Asriel also mentions that Chara laughed hysterically when the two accidentally poisoned Asgore by putting golden flower petals instead of butter in a butterscotch pie they made for him.