Flowey is the deuteragonist of Underfell. He tries to help Frisk, and knows how humans act towards monsters.
His background is known, but not truly explained by the end of the Pacifist Timeline.In-game,he appears to encourage the player to kill the monsters because of the "Kill or Be Killed" motto,but that idea was outdated and so was scrapped.
Flowey was once known as Asriel, King Asgore and Toriel's son. After Chara died of an illness, Asriel used Chara's soul to cross the barrier and become the Hyper Angel of Life. He gave Chara their wish of dying peacefully in a bed of golden flowers. Unfortunately, the humans thought he had killed Chara. Asriel refused to fight and showed mercy. The humans didn't accept, and Asriel got brutally attacked and burned. Barely alive, he made it back to the Underground, where he died. His dust blew onto a bed of golden flowers. One flower was injected with determination, possibly by Alphys. Then he became a living flower. Afraid of what his parents might think, he ran away.
The king was so devastated that he held an even stronger grudge against humanity and declared war. Toriel left Asgore and a new rule was declared. That rule was "Kill or Be Killed".
Flowey, like his Undertale counterpart, still believes in the "Kill or Be Killed" motto but is more on the "Be Killed" side. However, after meeting Frisk, he starts to believe in a new motto, "Save and Be Saved".
Flowey is shown to look the same as his Undertale counterpart. However, the petals are shown to be torn, similar to how Flowey appears at the end of the Photoshop Flowey fight. His eyes are black. His face is white or peach and his petals are gold.
Flowey is shown to be similar to Undertale Asriel - usually happy, but can also get upset and cry a lot. He is afraid of the monsters of the Underground and terrified of King Asgore, despite him being his father. Frisk still showed loving mercy and kindness to all monsters.
As stated before, Flowey follows the "Kill or Be Killed" motto, but would be killed instead. Instead he prefers his own motto, "Save and Be Saved." Despite this, Flowey could kill Frisk if he wanted to.
Flowey has the same powers as his Undertale counterpart, which is firing "friendliness pellets," or plain bullets. He can manipulate the pellets so they can either heal or damage things. He can also change faces. But instead of using them to show an evil personality, like in Undertale, he uses them to show other monsters that he's not weak.
| Normal Route : Omega Sans|
In the Genocide timeline, Flowey can't let Frisk leave, for the sake of innocent humans that may live above that Frisk might kill. Flowey steals the six souls and transforms into Alpha Flowey to finish off Frisk. This battle comes after the Sans fight and is the final battle of the Genocide Route.The fight may be about the same as the Undertale photoshop Flowey fight.
Asriel Dreemurr the God of Uberlife
After losing to Frisk as Alpha Flowey, Flowey begins to give up.
As a last resort he uses the souls to become his true and most powerful form; Asriel.
- Frisk - Flowey accompanies Frisk across the Underground. He really likes them and will do all he can to help them, they helped him create his own motto "save or be saved". In a genocidal timeline, he will try to put his feelings for them aside and fight them but will ultimately fail. He is shown to feel really guilty after attacking you near the start of the game and is very nice to you for the rest of it.
- Asgore - Flowey is terrified of Asgore, despite him being his son.
- Sans - Sans and Flowey hate each other.
- Toriel- Flowey is very scared of toriel, despite being her son wanting to avoid her entirely in the ruins, and often feels sad talking about her as he says "she used to be the kindest monster ever."