Originally I Only Had Raven But The Idea Then Spiraled As I Had To Make Everything I Wanted To Share Fit Together Along Side My Other Oc's - Tumblr Posts

Undertale AU

The Au is called Underwing. It's a bit more unique than other au's not just in how some characters look but also in how somethings are gone entirely. [see tags]

Overview

The monster's lost the war earlier than their other counterparts. After the monster's were sealed underground they explored their new home and discovered it was many degrees hotter than the above world. As the years went by they settled down until the first creature appeared. It viciously attacked the monsters causing them to flee. As more and more creatures appeared the monsters knew they had to adapt and as they did, so did their environment. The monsters grew giant trees which they then created homes around building bridges to connect them to one another. They also grew to have bird feathers on their clothes. Some became more bird-like than others. The culture also adapts with the monsters. After this the same timeline follows up until we get to Frisk. Frisk goes through with a Neutral run before going on to do a Genocide run. Raven is the only survivor and the Genocide run causes the world to glitch. Once Raven returns home, the AU is entirely empty. No human, no monsters, even the other human souls seem to be missing. The only living things around were the Creatures.

Before

When Frisk first falls into the underground they land on a large suspended net. It has a couple of vines wrapped around the edges. Flowey is an Oleander flower instead of the regular yellow. Toriel comes and saves you, she has iridescent hummingbird feathers on her outfit. 

The Ruins are built into redwood trees and the occasional normal oak trees. The bridges are a deepish red like the trees and some seem to be the tree branches warped into bridges. Napstablook is still a ghost but as a Potoo. The Froggits have Frogmouth feathers along their backs, and Whimsun looks like a Humming-bird Hawk-moth, Moldsmal, Loox, Migosp, and Vegitoid are all the same and so is the spider bake sale. After leaving the Ruins Frisk falls again and lands on another net and are now in the Leaffall outskirts

Leaffall is the Snowdin of this place except there's no snow. It's all trees, Oak, Pine, and much more. Sans is a female but continues to go by Sans. She doesn't have any feathers when Frisk meets her and instead has down along the edge of her hoodie. Papyrus has Greater Bird-of-Paradise feathers along the end of his scarf. As Frisk travels instead of the normal piles of snow there'll be leaf piles. The Royal Guard is referred to as the Royal Flock. Snowdrake and Chilldrake both have Muscovy Duck feathers, Icecap has a Pileated Woodpecker feathers, Gryftrot has partridge feathers and his horns have vines growing on them along with a few tiny nests, Dogamy and Dogaressa have lovebird feathers. Doggo is a Catahoula Leopard Dog, Lesser Dog is a Treeing Walker Coonhound, and Greater Dog is a New Guinea Singing Dog. The Snowman is just a voice coming from a hollowed our tree and eyes. They give Frisk a pinecone to take. Grillby is a Phoenix. The other residents are the same. 

Next is Lavafall which takes the place of Waterfall. As the name suggests, instead of water it's all lava. The trees don't have any leaves and are all charred and some are on fire but don't seem to be burning. Most of the bridges still have some wood to them but there are parts that have been replaced by stone. The monsters that would usually be aquatic are now built to survive in lava. Monster Kid is now Monster Hatchling and has Kiwi feathers on his outfit. Undyne is an Osprey, Mad Dummy is a cassowary. There are no echo flowers in the area. Onionsan appears to be a fire bird from Russian folktales, Aaron has a tail of fire and Woshua instead has lava instead of water. Shyrien has Red-eyed Vireo feathers as a part of her hair. The Temmies have finch feathers except for Bob who has Waxwing feathers. Gerson is a Golden Eagle with messy feathers. 

Onwards is Sandland taking the place of Hotland. Before entering Frisk takes a pair of goggles and mask from a nearby box. Hotland is constantly having sandstorms with the bridges swaying while the trees built near them, Palm and Acacia, stay sturdy against the high winds. Alphys has Greater Horned Owl feathers on her lab coat, Mettaton has Peacock feathers and his Neo form is him as a full peacock, Muffet is a Goliath Birdeater, Royal Flock 01 and 02 both have armor with Greater Roadrunner feathers on their shoulders. Burgerpants is some sort of parrot, Bratty has Egyptian Plover feathers she added to her hair, Catty has Egret feathers she added to her nails. Instead of meeting amalgamations, Frisk would stumble upon some of the Creatures Alphas has and is able to drive them away. 

Last is New Home. It's a lot like the Ruins just minus the vines. Asgore has Philippine Eagle feathers on his entire cape and his trident is made of his feathers. Asriel would have Ivory-billed woodpecker feathers on his outfit.

Now

Since all of the original residents are dead except for Sans/ Raven the AU has made some changes. The original house the skeletons had before was expanded and now houses Raven, Blackbird, Crow, and Robin and has a few extra rooms. The Library was torn down and expanded also. Most of the areas are left abandoned since the four live mostly in Leaffall and last parts of the Ruins. Parts of the bridges outside Leaffall have fallen in disrepair and the only way to get across is to have the ability to travel through air either through flying, floating, or riding something or be able to travel through the trees by climbing and jumping. The Core doesn't even work half the time so the few lights available are in Leaffall anyways and they're powered independently by a generator in the library.

The AU itself is also hard to find. It seems to mostly be accessible to those who are running from something or looking for something. This may be a new home, a place to belong, or someone they know. Most people who do appear here don't stay since the AU is unforgiving in nature and takes more than it gives. The amount of skill needed to just travel to other parts of the AU and the general heat definitely has people thinking twice of staying.

Other

I might do other post either about the culture of the au, or what the oc's I have are like, most likely Raven and Blackbird first. I'll definitely be doing post on The Under and the Creatures that live down there.