Flowey is the Incarnation of Despair.
Flowey has a small green root, big yellow petals and a white core.His face has black simple eyes and a mouth(when creepy black around the core with white dots for eyes).
Despite his first appearance, he is no innocent happy go lucky flower. He dangerously loves to manipulate people and trick people either to complete his schemes to get them in a position to kill his victims. He is very crooked and loves to see others suffer. He wants to become a complete god so he can control and make many suffer.
He was born as the Incarnation of Despair from the blood of Chara and the dust of Asriel, the god of hope. After that, he follow the corrupted Chara who allowed him, as long as he doesn't stay too close.