Flowerfell Sans is an alternate version of Underfell Sans. In the beginning, when Frisk first fell, he killed them right when they got to Snowdin, but after a very long period of time, he realizes that Frisk grew more flowers on their face every time they died. Eventually, Frisk lost their sight due to the flowers growing over their eyes. When he realized that, despite him causing them pain, they are still kind to him, he began to guide Frisk along on their journey along with Flowey.
Flowerfell Sans looks a lot like Underfell Sans, with the gray jacket, spiked teeth, single gold tooth, and red T-shirt, but there are some differences. He is constantly wearing a black scarf with red stripes and a necklace which looks like a SAVE point. He also has a single red eye. Sometimes he is depicted without his jacket.