WARNING: Contains Spoilers For Deltarune In Undertale the 3 (and sometimes 5) main Gaster Followers, or "Goners" always have a corresponding character in Deltarune. For example, Gaster Follower #1 is a grayscale version of Ficus Licker, who also appears in Deltarune. I will mainly be talking about the Goner's equivalents, along with briefly talking about how the Goners could be pieces of Gaster themselves. Gaster Follower #3 has a fully colored version of themselves in Deltarune (The Striped Bird. Though there are differences in the two sprites. Gaster Follower #2 also has an identical (slightly altered) sprite in Deltarune. Goner Kid's corresponding character is the Deltarune version of Monster Kid. Why not the Undertale one? Well, because the spikes on their head match Goner Kid's, (They're on the right) but the Undertale Monster Kid's spikes are on the left, making Undertale Monster Kid and Goner Kid separate characters. Goner Clam Girl uniquely, does not have a reused, altered, or new sprite. Though there is an NPC that appears named "Clam Guy." And how could the Goner's be pieces of Gaster themselves? Well, our main evidence is from Gaster Follower #2. In fact he's not the one who speaks to us in the rare 20% event. It's the piece of Gaster. But no! If you look close, The Gaster Piece is actually part of his hand meaning he IS the one talking. This also means he's a piece of Gaster! Anyway, that's all my evidence for The "Ferris Wheel Theory."
Toby Fox and Temmie Chang.