Flowey is the main antagonist of Undertale.He had seen all of the timeline’s possibilities.
He was the one controlling timelines and resets before you fell down and changed everything in the underground.He is egoistic , got god complex , smart ,soulless, manipulative,short tempered.He is a golden flower with no arms nor legs.He was once Asriel , son of Toriel and Asgore and best friend of first fallen human-Chara.Even though his tough facade , he is still a lost child deep inside.
Post pacifist.