Flowey

Flowey is a fictional character and the main antagonist of the role-playing video game "Undertale", created by Toby Fox. He appears for most of the game in the form of an innocuous sentient flower with a sadistic and psychopathic personality. It is later revealed that he is the reincarnation of Asriel Dreemurr, a young monster prince who was killed by humans. Commentators have praised Flowey's characterization, well-constructed backstory, and boss fights involving the character.
Appearances.
The player first encounters Flowey, who appears as an unassuming flower with a face in the middle, at the very start of the game. He attacks the player under the pretense of being a helpful monster who will award the player with "friendliness pellets," which are actually harmful bullets. He also tells the player to level up by increasing their LOVE, which unbeknownst to the player stands for "level of violence", therefore in actuality encouraging violence against other monsters, stating his philosophy "KILL or BE killed." He is chased away by Toriel before he can kill the player, only returning after the player has fought her.
Following the player throughout the game, Flowey returns after the fight against Asgore, finishing him off if the player tries to spare him, to get him out of the way in order to obtain the collected human souls. Using the power of the souls, he becomes Photoshop Flowey (also known as Omega Flowey) and takes on a hideous and gigantic form that clashes in art style with the rest of the game. When the player defeats him, he tells the player to complete the game without collecting any LOVE if he is spared, precipitating the game's "Pacifist Route", if the player has not done so already.
Asriel Dreemurr.
When the player encounters the True Lab area of the game, they learn the origins of Flowey—that he was the son of Toriel and Asgore, being named Asriel with half of each of their names. An only child, Asriel became best friends with Chara, the first fallen human. Chara devised a plan to commit suicide by eating poisonous flowers, combine their soul with Asriel's and break through the barrier and free the monsters from the barrier. When this plan was executed, Asriel transformed into a powerful being. As the control of the body was shared between Chara and Asriel, it's the human who took their own body to the human village and put it in the center of the village. Unfortunately, the fusion was attacked by the humans who believed Asriel had killed Chara. Chara tried to fight back but Asriel resisted them and walked away. The humans mortally wounded Asriel and, upon returning home, he collapsed, his dust scattering over golden flowers. Asriel's consciousness was restored as a sentient flower as a result of scientific experimentation. In the genocide route of the game, Flowey tells the player—instead of the monsters telling you the story of Asriel and Chara—that after awakening as a flower, Asriel reunited with his parents but was upset because he no longer felt love towards them. He then realized he had the ability to reset time after almost committing suicide, and abandoned his old identity to continue living his life as Flowey.
At the end of the True Pacifist route, Flowey retakes the souls of the fallen humans and absorbs the souls of all the monsters of the underground to take the form of an all-powerful older Asriel. Asriel, mistakenly thinking the playable character Frisk is Chara, wants them to keep playing with him over and over. Frisk "SAVES" Asriel and reaches out to him, leading the monster to emotionally break down and admit his insecurity and loneliness. Asriel regains his empathy and reverts to his original appearance as a child. He apologizes for his misdeeds and uses his power to break the barrier, thus freeing the monsters. He ultimately reverts to Flowey and is unable to feel love but is able to leave the underground.
Before the end of the genocide route of the game, when Flowey flees from Frisk, Frisk brutally wounds Asgore and Flowey finishes him off in order to convince the protagonist (who he thinks to be Chara) that he never betrayed them. Flowey begs for mercy, saying that he can be helpful and won’t screw up again, revealing himself to be Asriel by mimicking his former face and voice. He ultimately gets killed in the most terrible way possible if the player go through his dialogue. The only way to spare him is to exit and reset the game.
In Chapter 1 of "Deltarune", which takes place in a different universe than "Undertale", Asriel appears as the older brother of Kris, the main protagonist, and is said to be attending college. When Kris and their classmate Susie enter the Dark World, they meet Ralsei, a 'prince from the dark' whose appearance and personality is similar to that of Asriel. Just before Kris and Susie leave the Dark World, Ralsei reveals his true appearance, which heavily resembles Asriel. Additionally, Ralsei's name is an anagram of Asriel.
Reception.
Flowey has received generally positive reception. Flowey was a runner-up for USGamer's best characters of 2015, citing his knowledge of everything the player "has been up to", which may leave the player "a little stunned." USGamer also called the older Asriel "exactly the kind of thing a suffering pre-teen would design if they had possession of God's own wrath." Game Informer called Flowey one of the top 10 fourth wall breaking moments in games, calling him a "crazed talking flower". Zack Furniss of Destructoid stated that the battle against Flowey was one of his favorite gaming moments of 2015, saying that while he was apprehensive about playing the game, the fact that "a small flower ends up being a Photoshopped monster that can destroy in seconds", "sold" him on the game. Calling Photoshop Flowey "wonderfully disturbing", he called the boss and how it affected the player's save file what would stay with him the longest.
Jason Schreier of "Kotaku" called the fight against Flowey's true form as Asriel "one of the greatest final boss fights in RPG history", saying that it rivaled "games like "EarthBound" and "Chrono Trigger" in sheer, gut-wrenching poignancy." Stating that he has "one hell of a theme song", he praised the entire fight sequence as "spectacular", saying that it "justifies even the slowest of "Undertale"'s setups". "Thegamer" ranked Flowey as the 8th best character among the main cast, opining that his fight is "one of the most intense boss battles in modern gaming history".