Flowey

Flowey in Undertale (Or IS it..?) is one of the few non-glitched characters in the game.

Difference from Undertale Flowey
Flowey in Undertale (Or IS it..?) is different from Undertale Flowey in a way:
 * He tries to help the player. (normal Flowey tries to kill you.)

The Human
Flowey is friends with the human, and tells them about the accident.

Other Monsters
Flowey despises of monsters who try to kill his friends, but is friends with Sans, Toriel, Alphys, Mettaton, Papyrus, and Asgore.

Genocide Route
See Flowey/Genocide Boss Fight.

Trivia

 * Flowey, Frisk, and Chara are the only coloured characters in Undertale (Or IS it..?).