Flowey

When you first tumble into the Underground, Flowey is the very first entity you meet. He pretends to teach you the basics of battle mechanics, attempting to trick you into absorbing fatal damage. ​Behind his cheery facade lies a tragic, soulless vessel. Created when Alphys injected Determination into one of the Queen's golden flowers, Flowey carries the essence of Asriel Dreemurr—the fallen prince of the Underground. Devoid of a Monster Soul, he is entirely incapable of feeling love, empathy, or compassion. Trapped in a digital purgatory of infinite boredom, he discovered he possessed the power to SAVE, LOAD, and RESET the world's timeline, treating every inhabitant of the Underground like code in an interactive sandbox until the player's arrival stripped him of control.