Flowey

Asriel Dreemurr was subjected to Determination by W.D Gaster and was fused into his favorite yellow flower. When this occurred, he lost all emotions and resorts to sadism to try feeling, his pessimistic view of the world being cut down to 'Kill or be killed'. Ever since his transformation, he decided to create a new name as Asriel became less himself after encountering every reset and timeline, having saved and kill almost everyone, except Sans, who proved too powerful for him. But he lost to power to manipulate time when Frisk entered Mt. Ebott. Deep down, he still cares for Frisk, and the traces of his best friend Chara that resides inside her.